A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat from this vulnerability is system availability.

The remote SUSE Linux SLES12 / SLES_SAP12 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2024:0539-1 advisory.

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is     executed on the server-side. In case the library is used in a way where users can influence the third     parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading     to a compromise of the remote target. (CVE-2019-14889)

  - libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.
    (CVE-2020-16135)

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating secret_hash of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

  - A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. This issue may     allow an authenticated client to cause a denial of service. (CVE-2023-1667)

  - A vulnerability was found in libssh, where the authentication check of the connecting client can be     bypassed in the`pki_verify_data_signature` function in memory allocation problems. This issue may happen     if there is insufficient memory or the memory usage is limited. The problem is caused by the return value     `rc,` which is initialized to SSH_ERROR and later rewritten to save the return value of the function call     `pki_key_check_hash_compatible.` The value of the variable is not changed between this point and the     cryptographic verification. Therefore any error between them calls `goto error` returning SSH_OK.
    (CVE-2023-2283)

  - The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other     products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the     extension negotiation message), and a client and server may consequently end up with a connection for     which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because     the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and     mishandles use of sequence numbers. For example, there is an effective attack against SSH's use of     ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in chacha20-poly1305@openssh.com and     (if CBC is used) the -etm@openssh.com MAC algorithms. This also affects Maverick Synergy Java SSH API     before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, PuTTY before 0.80,     AsyncSSH before 2.14.2, golang.org/x/crypto before 0.17.0, libssh before 0.10.6, libssh2 through 1.11.0,     Thorn Tech SFTP Gateway before 3.4.6, Tera Term before 5.1, Paramiko before 3.4.0, jsch before 0.2.15,     SFTPGo before 2.5.6, Netgate pfSense Plus through 23.09.1, Netgate pfSense CE through 2.7.2, HPN-SSH     through 18.2.0, ProFTPD before 1.3.8b (and before 1.3.9rc2), ORYX CycloneSSH before 2.3.4, NetSarang     XShell 7 before Build 0144, CrushFTP before 10.6.0, ConnectBot SSH library before 2.2.22, Apache MINA sshd     through 2.11.0, sshj through 0.37.0, TinySSH through 20230101, trilead-ssh2 6401, LANCOM LCOS and     LANconfig, FileZilla before 3.66.4, Nova before 11.8, PKIX-SSH before 14.4, SecureCRT before 9.4.3,     Transmit5 before 5.10.4, Win32-OpenSSH before 9.5.0.0p1-Beta, WinSCP before 6.2.2, Bitvise SSH Server     before 9.32, Bitvise SSH Client before 9.33, KiTTY through 0.76.1.13, the net-ssh gem 7.2.0 for Ruby, the     mscdex ssh2 module before 1.15.0 for Node.js, the thrussh library before 0.35.1 for Rust, and the Russh     crate before 0.40.2 for Rust. (CVE-2023-48795)

  - A flaw was found in libssh. By utilizing the ProxyCommand or ProxyJump feature, users can exploit     unchecked hostname syntax on the client. This issue may allow an attacker to inject malicious code into     the command of the features mentioned through the hostname parameter. (CVE-2023-6004)

  - A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by     different supported crypto backends. The return values from these were not properly checked, which could     cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as     an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures,     terminating the connection. (CVE-2023-6918)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2024:0525-1 advisory.

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is     executed on the server-side. In case the library is used in a way where users can influence the third     parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading     to a compromise of the remote target. (CVE-2019-14889)

  - libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.
    (CVE-2020-16135)

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

  - A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared     secrets during the lifetime of the session. One of them is called secret_hash and the other session_id.
    Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as     an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked     as long as these buffers were same. But the key re-exchange operation can also change the key exchange     method, which can be based on hash of different size, eventually creating secret_hash of different size     than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used     again during second key re-exchange. (CVE-2021-3634)

  - A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. This issue may     allow an authenticated client to cause a denial of service. (CVE-2023-1667)

  - A vulnerability was found in libssh, where the authentication check of the connecting client can be     bypassed in the`pki_verify_data_signature` function in memory allocation problems. This issue may happen     if there is insufficient memory or the memory usage is limited. The problem is caused by the return value     `rc,` which is initialized to SSH_ERROR and later rewritten to save the return value of the function call     `pki_key_check_hash_compatible.` The value of the variable is not changed between this point and the     cryptographic verification. Therefore any error between them calls `goto error` returning SSH_OK.
    (CVE-2023-2283)

  - The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other     products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the     extension negotiation message), and a client and server may consequently end up with a connection for     which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because     the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and     mishandles use of sequence numbers. For example, there is an effective attack against SSH's use of     ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in chacha20-poly1305@openssh.com and     (if CBC is used) the -etm@openssh.com MAC algorithms. This also affects Maverick Synergy Java SSH API     before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, PuTTY before 0.80,     AsyncSSH before 2.14.2, golang.org/x/crypto before 0.17.0, libssh before 0.10.6, libssh2 through 1.11.0,     Thorn Tech SFTP Gateway before 3.4.6, Tera Term before 5.1, Paramiko before 3.4.0, jsch before 0.2.15,     SFTPGo before 2.5.6, Netgate pfSense Plus through 23.09.1, Netgate pfSense CE through 2.7.2, HPN-SSH     through 18.2.0, ProFTPD before 1.3.8b (and before 1.3.9rc2), ORYX CycloneSSH before 2.3.4, NetSarang     XShell 7 before Build 0144, CrushFTP before 10.6.0, ConnectBot SSH library before 2.2.22, Apache MINA sshd     through 2.11.0, sshj through 0.37.0, TinySSH through 20230101, trilead-ssh2 6401, LANCOM LCOS and     LANconfig, FileZilla before 3.66.4, Nova before 11.8, PKIX-SSH before 14.4, SecureCRT before 9.4.3,     Transmit5 before 5.10.4, Win32-OpenSSH before 9.5.0.0p1-Beta, WinSCP before 6.2.2, Bitvise SSH Server     before 9.32, Bitvise SSH Client before 9.33, KiTTY through 0.76.1.13, the net-ssh gem 7.2.0 for Ruby, the     mscdex ssh2 module before 1.15.0 for Node.js, the thrussh library before 0.35.1 for Rust, and the Russh     crate before 0.40.2 for Rust. (CVE-2023-48795)

  - A flaw was found in libssh. By utilizing the ProxyCommand or ProxyJump feature, users can exploit     unchecked hostname syntax on the client. This issue may allow an attacker to inject malicious code into     the command of the features mentioned through the hostname parameter. (CVE-2023-6004)

  - A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by     different supported crypto backends. The return values from these were not properly checked, which could     cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as     an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures,     terminating the connection. (CVE-2023-6918)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Rocky Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2020:4545 advisory.

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is     executed on the server-side. In case the library is used in a way where users can influence the third     parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading     to a compromise of the remote target. (CVE-2019-14889)

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of F5 Networks BIG-IP installed on the remote host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the K05295501 advisory.

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote AlmaLinux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ALSA-2020:4545 advisory.

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is     executed on the server-side. In case the library is used in a way where users can influence the third     parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading     to a compromise of the remote target. (CVE-2019-14889)

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote NewStart CGSL host, running version MAIN 6.02, has libssh packages installed that are affected by multiple vulnerabilities:

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is     executed on the server-side. In case the library is used in a way where users can influence the third     parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading     to a compromise of the remote target. (CVE-2019-14889)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote CentOS Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the CESA-2020:4545 advisory.

  - libssh: unsanitized location in scp could lead to unwanted command execution (CVE-2019-14889)

  - libssh: denial of service when handling AES-CTR (or DES) ciphers (CVE-2020-1730)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 8 host has a package installed that is affected by a vulnerability as referenced in the RHSA-2020:5218 advisory.

  - libssh: denial of service when handling AES-CTR (or DES) ciphers (CVE-2020-1730)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2020-4545 advisory.

  - A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully     initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat     from this vulnerability is system availability. (CVE-2020-1730)

  - A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8.
    When the libssh SCP client connects to a server, the scp command, which includes a user-provided path, is     executed on the server-side. In case the library is used in a way where users can influence the third     parameter of the function, it would become possible for an attacker to inject arbitrary commands, leading     to a compromise of the remote target. (CVE-2019-14889)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2020:4545 advisory.

  - libssh: unsanitized location in scp could lead to unwanted command execution (CVE-2019-14889)

  - libssh: denial of service when handling AES-CTR (or DES) ciphers (CVE-2020-1730)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

According to the version of the libssh package installed, the EulerOS Virtualization for ARM 64 installation on the remote host is affected by the following vulnerability :

  - A flaw was found in libssh versions before 0.8.9 and     before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could     crash when the connection hasn't been fully initialized     and the system tries to cleanup the ciphers when     closing the connection. The biggest threat from this     vulnerability is system availability.(CVE-2020-1730)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The libssh team reports (originally reported by Yasheng Yang from Google) :

A malicious client or server could crash the counterpart implemented with libssh AES-CTR ciphers are used and don't get fully initialized.
It will crash when it tries to cleanup the AES-CTR ciphers when closing the connection.

According to the version of the libssh package installed, the EulerOS installation on the remote host is affected by the following vulnerability :

  - A flaw was found in libssh versions before 0.8.9 and     before 0.9.4 in the way it handled AES-CTR (or DES     ciphers if enabled) ciphers. The server or client could     crash when the connection hasn't been fully initialized     and the system tries to cleanup the ciphers when     closing the connection. The biggest threat from this     vulnerability is system availability.(CVE-2020-1730)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Fixes CVE-2020-1730

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for libssh fixes the following issues :

  - CVE-2020-1730: Fixed a possible denial of service when     using AES-CTR (bsc#1168699).

This update was imported from the SUSE:SLE-15-SP1:Update update project.

The remote host is affected by the vulnerability described in GLSA-202004-08 (libssh: Denial of service)

    It was discovered that libssh could crash when AES-CTR ciphers are used.
  Impact :

    A remote attacker running a malicious client or server could possibly       crash the counterpart implemented with libssh and cause a Denial of       Service condition.
  Workaround :

    Disable AES-CTR ciphers. If you implement a server using libssh it is       recommended to use a prefork model so each session runs in an own       process.

Yasheng Yang discovered that libssh incorrectly handled AES-CTR ciphers. A remote attacker could possibly use this issue to cause libssh to crash, resulting in a denial of service.

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for libssh fixes the following issues :

CVE-2020-1730: Fixed a possible denial of service when using AES-CTR (bsc#1168699).

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
190835	SUSE SLES12 Security Update : libssh (SUSE-SU-2024:0539-1)	Nessus	SuSE Local Security Checks	high
190754	SUSE SLES15 Security Update : libssh (SUSE-SU-2024:0525-1)	Nessus	SuSE Local Security Checks	high
184708	Rocky Linux 8 : libssh (RLSA-2020:4545)	Nessus	Rocky Linux Local Security Checks	high
184231	F5 Networks BIG-IP : libssh vulnerability (K05295501)	Nessus	F5 Networks Local Security Checks	medium
157706	AlmaLinux 8 : libssh (ALSA-2020:4545)	Nessus	Alma Linux Local Security Checks	high
147245	NewStart CGSL MAIN 6.02 : libssh Multiple Vulnerabilities (NS-SA-2021-0069)	Nessus	NewStart CGSL Local Security Checks	high
145943	CentOS 8 : libssh (CESA-2020:4545)	Nessus	CentOS Local Security Checks	high
143238	RHEL 8 : Red Hat Virtualization (RHSA-2020:5218)	Nessus	Red Hat Local Security Checks	medium
142768	Oracle Linux 8 : libssh (ELSA-2020-4545)	Nessus	Oracle Linux Local Security Checks	high
142391	RHEL 8 : libssh (RHSA-2020:4545)	Nessus	Red Hat Local Security Checks	high
137806	EulerOS Virtualization for ARM 64 3.0.6.0 : libssh (EulerOS-SA-2020-1699)	Nessus	Huawei Local Security Checks	medium
135795	FreeBSD : Client/server denial of service when handling AES-CTR ciphers (3d7dfd63-823b-11ea-b3a8-240a644dd835)	Nessus	FreeBSD Local Security Checks	medium
135742	EulerOS 2.0 SP8 : libssh (EulerOS-SA-2020-1509)	Nessus	Huawei Local Security Checks	medium
135727	Fedora 31 : libssh (2020-5a77f0d68f)	Nessus	Fedora Local Security Checks	medium
135452	openSUSE Security Update : libssh (openSUSE-2020-510)	Nessus	SuSE Local Security Checks	medium
135426	GLSA-202004-08 : libssh: Denial of service	Nessus	Gentoo Local Security Checks	medium
135399	Ubuntu 18.04 LTS : libssh vulnerability (USN-4327-1)	Nessus	Ubuntu Local Security Checks	medium
135393	SUSE SLES12 Security Update : libssh (SUSE-SU-2020:0968-1)	Nessus	SuSE Local Security Checks	medium
135392	SUSE SLED15 / SLES15 Security Update : libssh (SUSE-SU-2020:0967-1)	Nessus	SuSE Local Security Checks	medium

Detections

Analytics

CVE-2020-1730

medium

Tenable Plugins

high

high

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medium

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medium

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medium