CVE-2020-14405

An issue was discovered in LibVNCServer before 0.9.13. libvncclient/rfbproto.c does not limit TextChat size.

LibVNCServer is a C library that enables you to implement VNC server functionality into own programs.

Security Fix(es):

• libvncserver: uninitialized memory contents are vulnerable to Information Leak (CVE-2018-21247)

• libvncserver: buffer overflow in ConnectClientToUnixSock() (CVE-2019-20839)

• libvncserver: libvncserver/rfbregion.c has a NULL pointer dereference (CVE-2020-14397)

• libvncserver: libvncclient/rfbproto.c does not limit TextChat size (CVE-2020-14405)

• libvncserver: libvncserver/rfbserver.c has a divide by zero which could result in DoS (CVE-2020-25708)

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 Rocky Linux 8.4 Release Notes linked from the References section.

An issue was discovered in LibVNCServer before 0.9.13. libvncclient/rfbproto.c does not limit TextChat size.

LibVNCServer is a C library that enables you to implement VNC server functionality into own programs.

Security Fix(es):

• libvncserver: uninitialized memory contents are vulnerable to Information Leak (CVE-2018-21247)

• libvncserver: buffer overflow in ConnectClientToUnixSock() (CVE-2019-20839)

• libvncserver: libvncserver/rfbregion.c has a NULL pointer dereference (CVE-2020-14397)

• libvncserver: libvncclient/rfbproto.c does not limit TextChat size (CVE-2020-14405)

• libvncserver: libvncserver/rfbserver.c has a divide by zero which could result in DoS (CVE-2020-25708)

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 AlmaLinux Release Notes linked from the References section.

Updated libvncserver packages fix security vulnerabilities:

libvncclient/sockets.c in LibVNCServer had a buffer overflow via a long socket filename (CVE-2019-20839).

libvncserver/rfbregion.c had a NULL pointer dereference (CVE-2020-14397).

Byte-aligned data was accessed through uint32_t pointers in libvncclient/rfbproto.c (CVE-2020-14399).

Byte-aligned data was accessed through uint16_t pointers in libvncserver/translate.c (CVE-2020-14400).

libvncserver/scale.c had a pixel_value integer overflow (CVE-2020-14401).

libvncserver/corre.c allowed out-of-bounds access via encodings (CVE-2020-14402).

libvncserver/hextile.c allowed out-of-bounds access via encodings (CVE-2020-14403).

libvncserver/rre.c allowed out-of-bounds access via encodings (CVE-2020-14404).

libvncclient/rfbproto.c does not limit TextChat size (CVE-2020-14405).

The libvncserver package has been updated to version 0.9.13, fixing these issues and several others. See the release announcement for details.

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)