CVE-2021-31535

LookupCol.c in X.Org X through X11R7.7 and libX11 before 1.7.1 might allow remote attackers to execute arbitrary code. The libX11 XLookupColor request (intended for server-side color lookup) contains a flaw allowing a client to send color-name requests with a name longer than the maximum size allowed by the protocol (and also longer than the maximum packet size for normal-sized packets). The user-controlled data exceeding the maximum size is then interpreted by the server as additional X protocol requests and executed, e.g., to disable X server authorization completely. For example, if the victim encounters malicious terminal control sequences for color codes, then the attacker may be able to take full control of the running graphical session.

LookupCol.c in X.Org X through X11R7.7 and libX11 before 1.7.1 might allow remote attackers to execute arbitrary code. The libX11 XLookupColor request (intended for server-side color lookup) contains a flaw allowing a client to send color-name requests with a name longer than the maximum size allowed by the protocol (and also longer than the maximum packet size for normal-sized packets). The user-controlled data exceeding the maximum size is then interpreted by the server as additional X protocol requests and executed, e.g., to disable X server authorization completely. For example, if the victim encounters malicious terminal control sequences for color codes, then the attacker may be able to take full control of the running graphical session.

LookupCol.c in X.Org X through X11R7.7 and libX11 before 1.7.1 might allow remote attackers to execute arbitrary code. The libX11 XLookupColor request (intended for server-side color lookup) contains a flaw allowing a client to send color-name requests with a name longer than the maximum size allowed by the protocol (and also longer than the maximum packet size for normal-sized packets). The user-controlled data exceeding the maximum size is then interpreted by the server as additional X protocol requests and executed, e.g., to disable X server authorization completely. For example, if the victim encounters malicious terminal control sequences for color codes, then the attacker may be able to take full control of the running graphical session.

Core X11 protocol client library.

Security Fix(es):

LookupCol.c in X.Org X through X11R7.7 and libX11 before 1.7.1 might allow remote attackers to execute arbitrary code. The libX11 XLookupColor request (intended for server-side color lookup) contains a flaw allowing a client to send color-name requests with a name longer than the maximum size allowed by the protocol (and also longer than the maximum packet size for normal-sized packets). The user-controlled data exceeding the maximum size is then interpreted by the server as additional X protocol requests and executed, e.g., to disable X server authorization completely. For example, if the victim encounters malicious terminal control sequences for color codes, then the attacker may be able to take full control of the running graphical session.(CVE-2021-31535)

The libX11 packages contain the core X11 protocol client library.

Security Fix(es):

• libX11: missing request length checks (CVE-2021-31535)

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 8.5 Release Notes linked from the References section.

LookupCol.c in X.Org X through X11R7.7 and libX11 before 1.7.1 might allow remote attackers to execute arbitrary code. The libX11 XLookupColor request (intended for server-side color lookup) contains a flaw allowing a client to send color-name requests with a name longer than the maximum size allowed by the protocol (and also longer than the maximum packet size for normal-sized packets). The user-controlled data exceeding the maximum size is then interpreted by the server as additional X protocol requests and executed, e.g., to disable X server authorization completely. For example, if the victim encounters malicious terminal control sequences for color codes, then the attacker may be able to take full control of the running graphical session.

The libX11 packages contain the core X11 protocol client library.

Security Fix(es):

• libX11: missing request length checks (CVE-2021-31535)

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.

• CVE-2018-14599: fix off-by-one writes in XListExtensions, XGetFontPath and XListFonts
• CVE-2018-14600: fix out-of-bounds write in XListExtensions and XGetFontPath
• CVE-2018-14598: fix crash on invalid reply in XListExtensions and XGetFontPath
• CVE-2021-31535: reject strings longer than USHRT_MAX before sending them on the wire
• CVE-2023-3138: add bounds checks for extension request, event and error codes
• CVE-2023-43787: fix integer overflow in XCreateImage leading to heap overflow

• CVE-2018-14599: fix off-by-one writes in XListExtensions, XGetFontPath and XListFonts
• CVE-2018-14600: fix out-of-bounds write in XListExtensions and XGetFontPath
• CVE-2018-14598: fix crash on invalid reply in XListExtensions and XGetFontPath
• CVE-2021-31535: reject strings longer than USHRT_MAX before sending them on the wire
• CVE-2023-3138: add bounds checks for extension request, event and error codes
• CVE-2023-43787: fix integer overflow in XCreateImage leading to heap overflow

XLookupColor() and other X libraries function lack proper validation of the length of their string parameters. If those parameters can be controlled by an external application (for instance a color name that can be emitted via a terminal control sequence) it can lead to the emission of extra X protocol requests to the X server (CVE-2021-31535).

This update for libX11 fixes the following issues:

• CVE-2021-31535: Fixed missing request length checks in libX11 (bsc#1182506).

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

This update for libX11 fixes the following issues:

• Regression in the fix for CVE-2021-31535, causing segfaults for xforms applications like fdesign (bsc#1186643)

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

This update for libX11 fixes the following issues:

• Regression in the fix for CVE-2021-31535, causing segfaults for xforms applications like fdesign (bsc#1186643)

These are all security issues fixed in the libX11-6-1.7.2-1.2 package on the GA media of openSUSE Tumbleweed.

This update for xorg-x11-libX11 fixes the following issues:

• Regression in the fix for CVE-2021-31535, causing segfaults for xforms applications like fdesign (bsc#1186643).

This update for libX11 fixes the following issues:

• CVE-2021-31535: Fixed missing request length checks in libX11 (bsc#1182506).

This update for libX11 fixes the following issues:

• CVE-2021-31535: Fixed missing request length checks in libX11 (bsc#1182506).

This update for libX11 fixes the following issues:

• Regression in the fix for CVE-2021-31535, causing segfaults for xforms applications like fdesign (bsc#1186643)

This update for libX11 fixes the following issues:

• Regression in the fix for CVE-2021-31535, causing segfaults for xforms applications like fdesign (bsc#1186643)

It was discovered that libx11 incorrectly validated certain parameter lengths. A remote attacker could possibly use this issue to trick libx11 into emitting extra X protocol requests.

USN-4966-1 fixed a vulnerability in libx11. This update provides the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

It was discovered that libx11 incorrectly validated certain parameter lengths. A remote attacker could possibly use this issue to trick libx11 into emitting extra X protocol requests.