libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

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

Note that Nessus relies on the presence of the package as reported by the vendor.

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

  - The RAND_bytes function in libssh before 0.6.3, when forking is enabled, does not properly reset the state     of the OpenSSL pseudo-random number generator (PRNG), which causes the state to be shared between children     processes and allows local users to obtain sensitive information by leveraging a pid collision.
    (CVE-2014-0017)

  - A vulnerability was found in libssh's server-side state machine. A malicious client could create channels     without first performing authentication, resulting in unauthorized access. (CVE-2018-10933)

  - A flaw was found with the libssh API function ssh_scp_new(). A user able to connect to a server using SCP     could execute arbitrary command using a user-provided path, leading to a compromise of the remote target.
    (CVE-2019-14889)

  - A flaw was found in libssh. A NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.
    (CVE-2020-16135)

  - A flaw was found in the way libssh 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 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 a vulnerability as referenced in the RLSA-2021:4387 advisory.

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

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 a vulnerability as referenced in the ALSA-2021:4387 advisory.

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

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 multiple vulnerabilities as referenced in the RHSA-2021:4750 advisory.

    The redhat-virtualization-host packages provide the Red Hat Virtualization Host. These packages include     redhat-release-virtualization-host, ovirt-node, and rhev-hypervisor. Red Hat Virtualization Hosts (RHVH)     are installed using a special build of Red Hat Enterprise Linux with only the packages required to host     virtual machines. RHVH features a Cockpit user interface for monitoring the host's resources and     performing administrative tasks.

    Security Fix(es):

    * kernel: out-of-bounds write due to a heap buffer overflow in __hidinput_change_resolution_multipliers()     of hid-input.c (CVE-2021-0512)

    * Ansible: ansible-connection module discloses sensitive info in traceback error message (CVE-2021-3620)

    * kernel: Insufficient validation of user-supplied sizes for the MSG_CRYPTO message type (CVE-2021-43267)

    * libssh: NULL pointer dereference in sftpserver.c if ssh_buffer_new returns NULL (CVE-2020-16135)

    For more details about the security issue(s), including the impact, a CVSS score, and other related     information, refer to the CVE page(s) listed in the References section.

    Bug Fix(es):

    * Red Hat Virtualization Host now includes packages from Red Hat Enterprise Linux 8.5. (BZ#1958101)

    * Red Hat Virtualization Host now includes packages from RHGS-3.5.z on RHEL-8 Batch #5. (BZ#1975175)

    * Red Hat Virtualization Host now includes the packages needed for using Managed Block Devices via     cinderlib. (BZ#1983021)

    * Red Hat Virtualization Host now includes openvswitch related packages from Fast Data Path 21.G release.
    (BZ#1998104)

    * Previously it was not possible to upgrade RHVH to version 4.4.8 when custom VDSM hooks were installed on     RHVH. This was caused by the VDSM hooks dependency on the concrete version of VDSM. The current release     allows users to maintain the VDSM dependency manually. In other words, if you want to upgrade from VDSM     X.Y.Z to version A.B.C, you must upgrade all VDSM hooks to the same A.B.C version. (BZ#2004469)

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues 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 a vulnerability as referenced in the ELSA-2021-4387 advisory.

    [0.9.4-3]
    - Fix CVE-2020-16135 NULL pointer dereference in sftpserver.c if       ssh_buffer_new returns NULL (#1862646)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

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 a vulnerability as referenced in the RHSA-2021:4387 advisory.

    libssh is a library which implements the SSH protocol. It can be used to implement client and server     applications.

    Security Fix(es):

    * libssh: NULL pointer dereference in sftpserver.c if ssh_buffer_new returns NULL (CVE-2020-16135)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

    Additional Changes:

    For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.5 Release Notes     linked from the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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 a vulnerability as referenced in the CESA-2021:4387 advisory.

  - libssh: NULL pointer dereference in sftpserver.c if ssh_buffer_new returns NULL (CVE-2020-16135)

Note that Nessus has not tested for this issue 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 installation on the remote host is affected by the following vulnerability :

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

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.

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 :

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

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.

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

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

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 remote host is affected by the vulnerability described in GLSA-202011-05 (libssh: Denial of service)

    libssh was found to have a NULL pointer dereference in tftpserver.c if       the function ssh_buffer_new returns NULL.
  Impact :

    An attacker could cause a possible Denial of Service condition.
  Workaround :

    There is no known workaround at this time.

Update to version 0.9.5

- https://www.libssh.org/2020/09/10/libssh-0-9-5/

  - Fixes CVE-2020-16135

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.

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by a vulnerability as referenced in the USN-4447-1 advisory.

    It was discovered that libssh incorrectly handled certain requests. An attacker could possibly use this     issue to cause a denial of service.

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

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

The code in src/sftpserver.c did not verify the validity of certain pointers and expected them to be valid. A NULL pointer dereference could have been occurred that typically causes a crash and thus a denial of service.

For Debian 9 stretch, this problem has been fixed in version 0.7.3-2+deb9u3.

We recommend that you upgrade your libssh packages.

For the detailed security status of libssh please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/libssh

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

ID	Name	Product	Family	Severity
223397	Linux Distros Unpatched Vulnerability : CVE-2020-16135	Nessus	Misc.	medium
206832	NewStart CGSL MAIN 6.02 : libssh Multiple Vulnerabilities (NS-SA-2024-0052)	Nessus	NewStart CGSL Local Security Checks	critical
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
185082	Rocky Linux 8 : libssh (RLSA-2021:4387)	Nessus	Rocky Linux Local Security Checks	medium
157502	AlmaLinux 8 : libssh (ALSA-2021:4387)	Nessus	Alma Linux Local Security Checks	medium
155654	RHEL 8 : Red Hat Virtualization Host security update [ovirt-4.4.9] 0-day (Important) (RHSA-2021:4750)	Nessus	Red Hat Local Security Checks	critical
155436	Oracle Linux 8 : libssh (ELSA-2021-4387)	Nessus	Oracle Linux Local Security Checks	medium
155225	RHEL 8 : libssh (RHSA-2021:4387)	Nessus	Red Hat Local Security Checks	medium
155136	CentOS 8 : libssh (CESA-2021:4387)	Nessus	CentOS Local Security Checks	medium
147610	EulerOS Virtualization 2.9.1 : libssh (EulerOS-SA-2021-1608)	Nessus	Huawei Local Security Checks	medium
147106	EulerOS Virtualization for ARM 64 3.0.6.0 : libssh (EulerOS-SA-2021-1584)	Nessus	Huawei Local Security Checks	medium
145158	EulerOS 2.0 SP3 : libssh (EulerOS-SA-2021-1088)	Nessus	Huawei Local Security Checks	medium
144119	EulerOS 2.0 SP8 : libssh (EulerOS-SA-2020-2517)	Nessus	Huawei Local Security Checks	medium
142241	GLSA-202011-05 : libssh: Denial of service	Nessus	Gentoo Local Security Checks	medium
140609	Fedora 32 : libssh (2020-f4f5e49cb8)	Nessus	Fedora Local Security Checks	medium
139367	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : libssh vulnerability (USN-4447-1)	Nessus	Ubuntu Local Security Checks	medium
139246	Debian DLA-2303-1 : libssh security update	Nessus	Debian Local Security Checks	medium

Detections

Analytics

CVE-2020-16135

medium

Tenable Plugins

medium

critical

high

high

medium

medium

critical

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium