An issue was discovered in LibVNCServer before 0.9.13. libvncserver/ws_decode.c can lead to a crash because of unaligned accesses in hybiReadAndDecode.

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

  - An issue was discovered in LibVNCServer before 0.9.13. libvncserver/ws_decode.c can lead to a crash     because of unaligned accesses in hybiReadAndDecode. (CVE-2019-20840)

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

According to the versions of the libvncserver package installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - An issue was discovered in LibVNCServer before 0.9.13. libvncserver/ws_decode.c can lead to a crash     because of unaligned accesses in hybiReadAndDecode. (CVE-2019-20840)

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 versions of the libvncserver package installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - A divide by zero issue was found to occur in     libvncserver-0.9.12. A malicious client could use this     flaw to send a specially crafted message that, when     processed by the VNC server, would lead to a floating     point exception, resulting in a denial of     service.(CVE-2020-25708)

  - An issue was discovered in LibVNCServer before 0.9.13.
    libvncserver/ws_decode.c can lead to a crash because of     unaligned accesses in     hybiReadAndDecode.(CVE-2019-20840)

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.

This update for LibVNCServer fixes the following issues :

security update fix CVE-2018-21247 [bsc#1173874], uninitialized memory contents are vulnerable to Information leak fix CVE-2019-20839 [bsc#1173875], buffer overflow in ConnectClientToUnixSock() fix CVE-2019-20840 [bsc#1173876], unaligned accesses in hybiReadAndDecode can lead to denial of service fix CVE-2020-14398 [bsc#1173880], improperly closed TCP connection causes an infinite loop in libvncclient/sockets.c fix CVE-2020-14397 [bsc#1173700], NULL pointer dereference in libvncserver/rfbregion.c fix CVE-2020-14399 [bsc#1173743], Byte-aligned data is accessed through uint32_t pointers in libvncclient/rfbproto.c. fix CVE-2020-14400 [bsc#1173691], Byte-aligned data is accessed through uint16_t pointers in libvncserver/translate.c. fix CVE-2020-14401 [bsc#1173694], potential integer overflows in libvncserver/scale.c fix CVE-2020-14402 [bsc#1173701], out-of-bounds access via encodings. fix CVE-2020-14403 [bsc#1173701], out-of-bounds access via encodings. fix CVE-2020-14404 [bsc#1173701], out-of-bounds access via encodings. fix CVE-2017-18922 [bsc#1173477], preauth buffer overwrite

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.

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-4434-1 advisory.

    Ramin Farajpour Cami discovered that LibVNCServer incorrectly handled certain malformed unix socket names.
    A remote attacker could exploit this with a crafted socket name, leading to a denial of service, or     possibly execute arbitrary code. (CVE-2019-20839)

    It was discovered that LibVNCServer did not properly access byte-aligned data. A remote attacker could     possibly use this issue to cause LibVNCServer to crash, resulting in a denial of service. This issue only     affected Ubuntu 18.04 LTS and Ubuntu 16.04 LTS. (CVE-2019-20840)

    Christian Beier discovered that LibVNCServer incorrectly handled anonymous TLS connections. A remote     attacker could possibly use this issue to cause LibVNCServer to crash, resulting in a denial of service.
    This issue only affected Ubuntu 20.04 LTS. (CVE-2020-14396)

    It was discovered that LibVNCServer incorrectly handled region clipping. A remote attacker could possibly     use this issue to cause LibVNCServer to crash, resulting in a denial of service. (CVE-2020-14397)

    It was discovered that LibVNCServer did not properly reset incorrectly terminated TCP connections. A     remote attacker could possibly use this issue to cause an infinite loop, resulting in a denial of service.
    (CVE-2020-14398)

    It was discovered that LibVNCServer did not properly access byte-aligned data. A remote attacker could     possibly use this issue to cause LibVNCServer to crash, resulting in a denial of service. (CVE-2020-14399,     CVE-2020-14400)

    It was discovered that LibVNCServer incorrectly handled screen scaling on the server side. A remote     attacker could use this issue to cause LibVNCServer to crash, resulting in a denial of service, or     possibly execute arbitrary code. (CVE-2020-14401)

    It was discovered that LibVNCServer incorrectly handled encodings. A remote attacker could use this issue     to cause LibVNCServer to crash, resulting in a denial of service, or possibly execute arbitrary code.
    (CVE-2020-14402, CVE-2020-14403, CVE-2020-14404)

    It was discovered that LibVNCServer incorrectly handled TextChat messages. A remote attacker could     possibly use this issue to cause LibVNCServer to crash, resulting in a denial of service. (CVE-2020-14405)

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

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

This update for LibVNCServer fixes the following issues :

  - security update

  - added patches fix CVE-2018-21247 [bsc#1173874],     uninitialized memory contents are vulnerable to     Information leak

  + LibVNCServer-CVE-2018-21247.patch fix CVE-2019-20839     [bsc#1173875], buffer overflow in     ConnectClientToUnixSock()

  + LibVNCServer-CVE-2019-20839.patch fix CVE-2019-20840     [bsc#1173876], unaligned accesses in hybiReadAndDecode     can lead to denial of service

  + LibVNCServer-CVE-2019-20840.patch fix CVE-2020-14398     [bsc#1173880], improperly closed TCP connection causes     an infinite loop in libvncclient/sockets.c

  + LibVNCServer-CVE-2020-14398.patch fix CVE-2020-14397     [bsc#1173700], NULL pointer dereference in     libvncserver/rfbregion.c

  + LibVNCServer-CVE-2020-14397.patch fix CVE-2020-14399     [bsc#1173743], Byte-aligned data is accessed through     uint32_t pointers in libvncclient/rfbproto.c.

  + LibVNCServer-CVE-2020-14399.patch fix CVE-2020-14400     [bsc#1173691], Byte-aligned data is accessed through     uint16_t pointers in libvncserver/translate.c.

  + LibVNCServer-CVE-2020-14400.patch fix CVE-2020-14401     [bsc#1173694], potential integer overflows in     libvncserver/scale.c

  + LibVNCServer-CVE-2020-14401.patch fix CVE-2020-14402     [bsc#1173701], out-of-bounds access via encodings.

  + LibVNCServer-CVE-2020-14402,14403,14404.patch fix     CVE-2017-18922 [bsc#1173477], preauth buffer overwrite

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

This update for LibVNCServer fixes the following issues :

security update

added patches fix CVE-2018-21247 [bsc#1173874], uninitialized memory contents are vulnerable to Information leak

  + LibVNCServer-CVE-2018-21247.patch fix CVE-2019-20839     [bsc#1173875], buffer overflow in     ConnectClientToUnixSock()

  + LibVNCServer-CVE-2019-20839.patch fix CVE-2019-20840     [bsc#1173876], unaligned accesses in hybiReadAndDecode     can lead to denial of service

  + LibVNCServer-CVE-2019-20840.patch fix CVE-2020-14398     [bsc#1173880], improperly closed TCP connection causes     an infinite loop in libvncclient/sockets.c

  + LibVNCServer-CVE-2020-14398.patch fix CVE-2020-14397     [bsc#1173700], NULL pointer dereference in     libvncserver/rfbregion.c

  + LibVNCServer-CVE-2020-14397.patch fix CVE-2020-14399     [bsc#1173743], Byte-aligned data is accessed through     uint32_t pointers in libvncclient/rfbproto.c.

  + LibVNCServer-CVE-2020-14399.patch fix CVE-2020-14400     [bsc#1173691], Byte-aligned data is accessed through     uint16_t pointers in libvncserver/translate.c.

  + LibVNCServer-CVE-2020-14400.patch fix CVE-2020-14401     [bsc#1173694], potential integer overflows in     libvncserver/scale.c

  + LibVNCServer-CVE-2020-14401.patch fix CVE-2020-14402     [bsc#1173701], out-of-bounds access via encodings.

  + LibVNCServer-CVE-2020-14402,14403,14404.patch fix     CVE-2017-18922 [bsc#1173477], preauth buffer overwrite

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.

New upstream bugfix/security release.

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.

ID	Name	Product	Family	Severity
250508	Linux Distros Unpatched Vulnerability : CVE-2019-20840	Nessus	Misc.	high
161534	EulerOS 2.0 SP3 : libvncserver (EulerOS-SA-2022-1740)	Nessus	Huawei Local Security Checks	high
159096	EulerOS 2.0 SP5 : libvncserver (EulerOS-SA-2022-1329)	Nessus	Huawei Local Security Checks	high
145732	EulerOS 2.0 SP8 : libvncserver (EulerOS-SA-2021-1153)	Nessus	Huawei Local Security Checks	high
139453	SUSE SLES12 Security Update : LibVNCServer (SUSE-SU-2020:2167-1)	Nessus	SuSE Local Security Checks	critical
138999	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : LibVNCServer vulnerabilities (USN-4434-1)	Nessus	Ubuntu Local Security Checks	medium
138984	openSUSE Security Update : LibVNCServer (openSUSE-2020-1056)	Nessus	SuSE Local Security Checks	critical
138828	openSUSE Security Update : LibVNCServer (openSUSE-2020-1025)	Nessus	SuSE Local Security Checks	critical
138751	openSUSE Security Update : LibVNCServer (openSUSE-2020-988)	Nessus	SuSE Local Security Checks	critical
138548	SUSE SLED15 / SLES15 Security Update : LibVNCServer (SUSE-SU-2020:1922-1)	Nessus	SuSE Local Security Checks	critical
138530	Fedora 32 : libvncserver (2020-1a4b1c8271)	Nessus	Fedora Local Security Checks	critical

Detections

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CVE-2019-20840

high

Tenable Plugins

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