CVE-2025-62231

A flaw was identified in the X.Org X server’s X Keyboard (Xkb) extension where improper bounds checking in the XkbSetCompatMap() function can cause an unsigned short overflow. If an attacker sends specially crafted input data, the value calculation may overflow, leading to memory corruption or a crash.

A flaw was identified in the X.Org X server’s X Keyboard (Xkb) extension where improper bounds checking in the XkbSetCompatMap() function can cause an unsigned short overflow. If an attacker sends specially crafted input data, the value calculation may overflow, leading to memory corruption or a crash.

X.Org X11 X server

Security Fix(es):

In X.Org X server 20.11 through 21.1.16, when a client application uses easystroke for mouse gestures, the main thread modifies various data structures used by the input thread without acquiring a lock, aka a race condition. In particular, AttachDevice in dix/devices.c does not acquire an input lock.(CVE-2022-49737)

A flaw was found in the X Rendering extension's handling of animated cursors. If a client provides no cursors, the server assumes at least one is present, leading to an out-of-bounds read and potential crash.(CVE-2025-49175)

A flaw was found in the Big Requests extension. The request length is multiplied by 4 before checking against the maximum allowed size, potentially causing an integer overflow and bypassing the size check.(CVE-2025-49176)

A flaw was found in the X server's request handling. Non-zero 'bytes to ignore' in a client's request can cause the server to skip processing another client's request, potentially leading to a denial of service.(CVE-2025-49178)

A flaw was found in the X Record extension. The RecordSanityCheckRegisterClients function does not check for an integer overflow when computing request length, which allows a client to bypass length checks.(CVE-2025-49179)

A flaw was found in the RandR extension, where the RRChangeProviderProperty function does not properly validate input. This issue leads to an integer overflow when computing the total size to allocate.(CVE-2025-49180)

A flaw was found in the X.Org X server and Xwayland when processing X11 Present extension notifications. Improper error handling during notification creation can leave dangling pointers that lead to a use-after-free condition. This can cause memory corruption or a crash, potentially allowing an attacker to execute arbitrary code or cause a denial of service.(CVE-2025-62229)

A flaw was discovered in the X.Org X server’s X Keyboard (Xkb) extension when handling client resource cleanup. The software frees certain data structures without properly detaching related resources, leading to a use-after-free condition. This can cause memory corruption or a crash when affected clients disconnect.(CVE-2025-62230)

A flaw was identified in the X.Org X server’s X Keyboard (Xkb) extension where improper bounds checking in the XkbSetCompatMap() function can cause an unsigned short overflow. If an attacker sends specially crafted input data, the value calculation may overflow, leading to memory corruption or a crash.(CVE-2025-62231)

Xwayland is an X server for running X clients under Wayland. %package devel Summary: Development package Requires: pkgconfig %description devel The development package provides the developmental files which are necessary for developing Wayland compositors using Xwayland. %prep %autosetup -n xwayland- -p1 %build %meson \ -Ddefault_font_path="catalogue:/etc/X11/fontpath.d,built-ins" \ -Dbuilder_string="Build ID: -" \ -Dxkb_output_dir=/lib/xkb \ -Dxcsecurity=true \ -Dglamor=true \ -Ddri3=true %meson_build

Security Fix(es):

A flaw was found in the X.Org X server and Xwayland when processing X11 Present extension notifications. Improper error handling during notification creation can leave dangling pointers that lead to a use-after-free condition. This can cause memory corruption or a crash, potentially allowing an attacker to execute arbitrary code or cause a denial of service.(CVE-2025-62229)

A flaw was identified in the X.Org X server’s X Keyboard (Xkb) extension where improper bounds checking in the XkbSetCompatMap() function can cause an unsigned short overflow. If an attacker sends specially crafted input data, the value calculation may overflow, leading to memory corruption or a crash.(CVE-2025-62231)

A flaw was found in the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violations and potentially a denial of service (DoS) or other severe impacts.(CVE-2026-33999)

A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.(CVE-2026-34001)

A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.(CVE-2026-34002)

A flaw was found in the X.Org X server's XKB key types request validation. A local attacker could send a specially crafted request to the X server, leading to an out-of-bounds memory access vulnerability. This could result in the disclosure of sensitive information or cause the server to crash, leading to a Denial of Service (DoS). In certain configurations, higher impact outcomes may be possible.(CVE-2026-34003)

['Hi all,\n\nCVEs have been issued now, please see inline below\n\nOn Tue, Jun 02, 2026 at 10:01:46AM +1000, Peter Hutterer wrote:', "=======================================================================\nX.Org Security Advisory: June 2, 2026 \n\nIssues in X.Org X server prior to 21.1.23 and Xwayland prior to 24.1.12\n=======================================================================\n\nMultiple issues have been found in the X server and Xwayland implementations\npublished by X.Org for which we are releasing security fixes for in\nxorg-server-21.1.23 and xwayland-24.1.12.\n\nNote that CVEs have been requested for these issues but did not get assigned in\ntime for this disclosure.\n\n* Font Alias Stack-based Buffer Overflow\n\n A mismatch between the X server and the libXfont2 library's maximum\n font name length can cause a stack buffer overflow during font alias\n resolution. The server allocates a 256 byte stack buffer but libXfont2's\n alias target name length is 1024 bytes.…

Xwayland is an X server for running X clients under Wayland. %package devel Summary: Development package Requires: pkgconfig %description devel The development package provides the developmental files which are necessary for developing Wayland compositors using Xwayland. %prep %autosetup -n xwayland- -p1 %build %meson \ -Ddefault_font_path="catalogue:/etc/X11/fontpath.d,built-ins" \ -Dbuilder_string="Build ID: -" \ -Dxkb_output_dir=/lib/xkb \ -Dxcsecurity=true \ -Dglamor=true \ -Ddri3=true %meson_build

Security Fix(es):

A flaw was found in the X.Org X server and Xwayland when processing X11 Present extension notifications. Improper error handling during notification creation can leave dangling pointers that lead to a use-after-free condition. This can cause memory corruption or a crash, potentially allowing an attacker to execute arbitrary code or cause a denial of service.(CVE-2025-62229)

A flaw was identified in the X.Org X server’s X Keyboard (Xkb) extension where improper bounds checking in the XkbSetCompatMap() function can cause an unsigned short overflow. If an attacker sends specially crafted input data, the value calculation may overflow, leading to memory corruption or a crash.(CVE-2025-62231)

A flaw was found in the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violations and potentially a denial of service (DoS) or other severe impacts.(CVE-2026-33999)

A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.(CVE-2026-34001)

A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.(CVE-2026-34002)

A flaw was found in the X.Org X server's XKB key types request validation. A local attacker could send a specially crafted request to the X server, leading to an out-of-bounds memory access vulnerability. This could result in the disclosure of sensitive information or cause the server to crash, leading to a Denial of Service (DoS). In certain configurations, higher impact outcomes may be possible.(CVE-2026-34003)

['Hi all,\n\nCVEs have been issued now, please see inline below\n\nOn Tue, Jun 02, 2026 at 10:01:46AM +1000, Peter Hutterer wrote:', "=======================================================================\nX.Org Security Advisory: June 2, 2026 \n\nIssues in X.Org X server prior to 21.1.23 and Xwayland prior to 24.1.12\n=======================================================================\n\nMultiple issues have been found in the X server and Xwayland implementations\npublished by X.Org for which we are releasing security fixes for in\nxorg-server-21.1.23 and xwayland-24.1.12.\n\nNote that CVEs have been requested for these issues but did not get assigned in\ntime for this disclosure.\n\n* Font Alias Stack-based Buffer Overflow\n\n A mismatch between the X server and the libXfont2 library's maximum\n font name length can cause a stack buffer overflow during font alias\n resolution. The server allocates a 256 byte stack buffer but libXfont2's\n alias target name length is 1024 bytes.…

Xwayland is an X server for running X clients under Wayland. %package devel Summary: Development package Requires: pkgconfig %description devel The development package provides the developmental files which are necessary for developing Wayland compositors using Xwayland. %prep %autosetup -n xwayland- -p1 %build %meson \ -Ddefault_font_path="catalogue:/etc/X11/fontpath.d,built-ins" \ -Dbuilder_string="Build ID: -" \ -Dxkb_output_dir=/lib/xkb \ -Dxcsecurity=true \ -Dglamor=true \ -Ddri3=true %meson_build

Security Fix(es):

A flaw was found in the X.Org X server and Xwayland when processing X11 Present extension notifications. Improper error handling during notification creation can leave dangling pointers that lead to a use-after-free condition. This can cause memory corruption or a crash, potentially allowing an attacker to execute arbitrary code or cause a denial of service.(CVE-2025-62229)

A flaw was identified in the X.Org X server’s X Keyboard (Xkb) extension where improper bounds checking in the XkbSetCompatMap() function can cause an unsigned short overflow. If an attacker sends specially crafted input data, the value calculation may overflow, leading to memory corruption or a crash.(CVE-2025-62231)

A flaw was found in the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violations and potentially a denial of service (DoS) or other severe impacts.(CVE-2026-33999)

A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.(CVE-2026-34001)

A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.(CVE-2026-34002)

A flaw was found in the X.Org X server's XKB key types request validation. A local attacker could send a specially crafted request to the X server, leading to an out-of-bounds memory access vulnerability. This could result in the disclosure of sensitive information or cause the server to crash, leading to a Denial of Service (DoS). In certain configurations, higher impact outcomes may be possible.(CVE-2026-34003)

['Hi all,\n\nCVEs have been issued now, please see inline below\n\nOn Tue, Jun 02, 2026 at 10:01:46AM +1000, Peter Hutterer wrote:', "=======================================================================\nX.Org Security Advisory: June 2, 2026 \n\nIssues in X.Org X server prior to 21.1.23 and Xwayland prior to 24.1.12\n=======================================================================\n\nMultiple issues have been found in the X server and Xwayland implementations\npublished by X.Org for which we are releasing security fixes for in\nxorg-server-21.1.23 and xwayland-24.1.12.\n\nNote that CVEs have been requested for these issues but did not get assigned in\ntime for this disclosure.\n\n* Font Alias Stack-based Buffer Overflow\n\n A mismatch between the X server and the libXfont2 library's maximum\n font name length can cause a stack buffer overflow during font alias\n resolution. The server allocates a 256 byte stack buffer but libXfont2's\n alias target name length is 1024 bytes.…

Xwayland is an X server for running X clients under Wayland. %package devel Summary: Development package Requires: pkgconfig %description devel The development package provides the developmental files which are necessary for developing Wayland compositors using Xwayland. %prep %autosetup -n xwayland- -p1 %build %meson \ -Ddefault_font_path="catalogue:/etc/X11/fontpath.d,built-ins" \ -Dbuilder_string="Build ID: -" \ -Dxkb_output_dir=/lib/xkb \ -Dxcsecurity=true \ -Dglamor=true \ -Ddri3=true %meson_build

Security Fix(es):

A flaw was identified in the X.Org X server’s X Keyboard (Xkb) extension where improper bounds checking in the XkbSetCompatMap() function can cause an unsigned short overflow. If an attacker sends specially crafted input data, the value calculation may overflow, leading to memory corruption or a crash.(CVE-2025-62231)

A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.(CVE-2026-34002)

A flaw was found in the X.Org X server's XKB key types request validation. A local attacker could send a specially crafted request to the X server, leading to an out-of-bounds memory access vulnerability. This could result in the disclosure of sensitive information or cause the server to crash, leading to a Denial of Service (DoS). In certain configurations, higher impact outcomes may be possible.(CVE-2026-34003)

['Hi all,\n\nCVEs have been issued now, please see inline below\n\nOn Tue, Jun 02, 2026 at 10:01:46AM +1000, Peter Hutterer wrote:', "=======================================================================\nX.Org Security Advisory: June 2, 2026 \n\nIssues in X.Org X server prior to 21.1.23 and Xwayland prior to 24.1.12\n=======================================================================\n\nMultiple issues have been found in the X server and Xwayland implementations\npublished by X.Org for which we are releasing security fixes for in\nxorg-server-21.1.23 and xwayland-24.1.12.\n\nNote that CVEs have been requested for these issues but did not get assigned in\ntime for this disclosure.\n\n* Font Alias Stack-based Buffer Overflow\n\n A mismatch between the X server and the libXfont2 library's maximum\n font name length can cause a stack buffer overflow during font alias\n resolution. The server allocates a 256 byte stack buffer but libXfont2's\n alias target name length is 1024 bytes. A font alias name between 257\n and 1023 bytes causes the X server to copy that name into the undersized\n stack buffer without further checks.\n\n Fixed in: xorg-server-21.1.23 and xwayland-24.1.12\n Fix:", 'Found by: Anonymous working with TrendAI Zero Day Initiative.\n (ZDI-CAN-30136)', 'This issue has been assigned CVE-2026-50256', '* XSYNC Use-After-Free in miSyncDestroyFence()\n\n A client that sets up multiple fence triggers can trigger a\n use-after-free function pointer call. An attacker would connect to the\n X server to set up a fence and await that fence, then a second X\n connection destroys the fence, causing the use-after-free.\n\n Fixed in: xorg-server-21.1.23 and xwayland-24.1.12\n Fix:', 'Found by: Anonymous working with TrendAI Zero Day Initiative.\n (ZDI-CAN-30159)', 'This issue has been assigned CVE-2026-50257', '* XKB Key Types Stack-based Buffer Overflow\n\n The X server has multiple stack buffers that are sized\n XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify\n …

Xwayland is an X server for running X clients under Wayland.

Security Fix(es):

• xorg: xmayland: Use-after-free in XPresentNotify structure creation (CVE-2025-62229)

• xorg: xwayland: Use-after-free in Xkb client resource removal (CVE-2025-62230)

• xorg: xmayland: Value overflow in XkbSetCompatMap() (CVE-2025-62231)

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.

Please update

X.Org is an open-source implementation of the X Window System. It provides the basic low-level functionality that full-fledged graphical user interfaces are designed upon.

Security Fix(es):

• xorg: xmayland: Use-after-free in XPresentNotify structure creation (CVE-2025-62229)

• xorg: xwayland: Use-after-free in Xkb client resource removal (CVE-2025-62230)

• xorg: xmayland: Value overflow in XkbSetCompatMap() (CVE-2025-62231)

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.

Xwayland is an X server for running X clients under Wayland.

Security Fix(es):

• xorg: xmayland: Use-after-free in XPresentNotify structure creation (CVE-2025-62229)

• xorg: xwayland: Use-after-free in Xkb client resource removal (CVE-2025-62230)

• xorg: xmayland: Value overflow in XkbSetCompatMap() (CVE-2025-62231)

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.

Please update

Virtual Network Computing (VNC) is a remote display system which allows users to view a computing desktop environment not only on the machine where it is running, but from anywhere on the Internet and from a wide variety of machine architectures. TigerVNC is a suite of VNC servers and clients.

Security Fix(es):

• xorg: xmayland: Use-after-free in XPresentNotify structure creation (CVE-2025-62229)

• xorg: xwayland: Use-after-free in Xkb client resource removal (CVE-2025-62230)

• xorg: xmayland: Value overflow in XkbSetCompatMap() (CVE-2025-62231)

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.

Virtual Network Computing (VNC) is a remote display system which allows users to view a computing desktop environment not only on the machine where it is running, but from anywhere on the Internet and from a wide variety of machine architectures. TigerVNC is a suite of VNC servers and clients.

Security Fix(es):

• xorg: xmayland: Use-after-free in XPresentNotify structure creation (CVE-2025-62229)

• xorg: xwayland: Use-after-free in Xkb client resource removal (CVE-2025-62230)

• xorg: xmayland: Value overflow in XkbSetCompatMap() (CVE-2025-62231)

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.

Xwayland is an X server for running X clients under Wayland.

Security Fix(es):

• xorg: xmayland: Use-after-free in XPresentNotify structure creation (CVE-2025-62229)

• xorg: xwayland: Use-after-free in Xkb client resource removal (CVE-2025-62230)

• xorg: xmayland: Value overflow in XkbSetCompatMap() (CVE-2025-62231)

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.