CVE-2026-93517

X.Org Server GLX RenderLarge Heap Buffer Overflow

A heap buffer overflow in handling GLX RenderLarge request where dataBytes exceeds cmdlen in X.org X server before 21.1.25 and XWayland before 24.1.14 that could be be triggered by an authenticated X client could cause crashes or code execution in X server context.

CVSS 4.0 · 8.5 High EPSS < 1% KEV · Not listed

Vendors

X.org X.orgg

Products

X Server Xwayland Xorg-x11-server

CVE-2025-62231

Xorg: xmayland: value overflow in xkbsetcompatmap()

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.

CVSS 3.1 · 7.3 High EPSS < 1% KEV · Not listed

Vendors

Debian Ibm Redhat and 1 more

Products

Debian Linux Aix Vios and 14 more

CVE-2025-62230

Xorg: xwayland: use-after-free in xkb client resource removal

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.

CVSS 3.1 · 7.3 High EPSS < 1% KEV · Not listed

Vendors

Debian Ibm Redhat and 1 more

Products

Debian Linux Aix Vios and 14 more

CVE-2023-5380

Xorg-x11-server: use-after-free bug in destroywindow

A use-after-free flaw was found in the xorg-x11-server. An X server crash may occur in a very specific and legacy configuration (a multi-screen setup with multiple protocol screens, also known as Zaphod mode) if the pointer is warped from within a window on one screen to the root window of the other screen and if the original window is destroyed followed by another window being destroyed.

CVSS 3.1 · 4.7 Medium EPSS < 1% KEV · Not listed

Vendors

Debian Fedoraproject Redhat and 1 more

Products

Debian Linux Fedora Enterprise Linux and 3 more

CVE-2026-50264

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: out-of-bounds heap write in dri2 drigetbuffers/drigetbufferswithformat

An out-of-bounds write flaw was found in the X.Org X server and Xwayland in DRIGetBuffers/DRIGetBuffersWithFormat. A client that requests multiple DRI2BufferBackLeft attachments and one DRI2BufferFrontLeft can trigger an out-of-bounds heap write. This may be used to crash the server, or for privilege escalation if the X server runs as root.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 8 more

CVE-2026-50261

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in syncchangecounter()

A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). A client that sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second client connection while changing those counters. This may be used to crash the server, or for privilege escalation if the X server runs as root.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 8 more

CVE-2026-50260

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in freecounter()

A use-after-free flaw was found in the X.Org X server and Xwayland in FreeCounter(). A client that sets up multiple SyncCounters and awaits on those triggers can trigger a use-after-free when destroying those counters via a second client connection. This may be used to crash the server, or for privilege escalation if the X server runs as root.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 8 more

CVE-2026-50258

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb key types due to unchecked shift levels

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 7 more

CVE-2026-50259

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb setmap request via mapwidths indexing

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org Xorg

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 9 more

CVE-2026-50257

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in misyncdestroyfence()

A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 8 more

CVE-2026-50256

Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libxfont2 name length mismatch

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. This may be used to crash the server, or for privilege escalation if the X server runs as root.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 8 more

CVE-2026-34003

Xorg: xwayland: x.org x server: information exposure and denial of service via out-of-bounds memory access

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.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 6 more

CVE-2026-34001

Xorg: xwayland: x.org x server: use-after-free vulnerability leads to server crash and potential memory corruption

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.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat X.org

Products

Enterprise Linux Enterprise Linux Eus Rhel Aus and 6 more

CVE-2025-26601

Xorg: xwayland: use-after-free in syncinittrigger()

A use-after-free flaw was found in X.Org and Xwayland. When changing an alarm, the values of the change mask are evaluated one after the other, changing the trigger values as requested, and eventually, SyncInitTrigger() is called. If one of the changes triggers an error, the function will return early, not adding the new sync object, possibly causing a use-after-free when the alarm eventually triggers.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat Tigervnc X.org

Products

Enterprise Linux Rhel Aus Rhel E4s and 6 more

CVE-2025-26600

Xorg: xwayland: use-after-free in playreleasedevents()

A use-after-free flaw was found in X.Org and Xwayland. When a device is removed while still frozen, the events queued for that device remain while the device is freed. Replaying the events will cause a use-after-free.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat Tigervnc X.org

Products

Enterprise Linux Rhel Aus Rhel E4s and 6 more

CVE-2025-26598

Xorg: xwayland: out-of-bounds write in createpointerbarrierclient()

An out-of-bounds write flaw was found in X.Org and Xwayland. The function GetBarrierDevice() searches for the pointer device based on its device ID and returns the matching value, or supposedly NULL, if no match was found. However, the code will return the last element of the list if no matching device ID is found, which can lead to out-of-bounds memory access.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat Tigervnc X.org

Products

Enterprise Linux Rhel Aus Rhel E4s and 6 more

CVE-2025-26599

Xorg: xwayland: use of uninitialized pointer in compredirectwindow()

An access to an uninitialized pointer flaw was found in X.Org and Xwayland. The function compCheckRedirect() may fail if it cannot allocate the backing pixmap. In that case, compRedirectWindow() will return a BadAlloc error without validating the window tree marked just before, which leaves the validated data partly initialized and the use of an uninitialized pointer later.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat Tigervnc X.org

Products

Enterprise Linux Rhel Aus Rhel E4s and 6 more

CVE-2025-26597

Xorg: xwayland: buffer overflow in xkbchangetypesofkey()

A buffer overflow flaw was found in X.Org and Xwayland. If XkbChangeTypesOfKey() is called with a 0 group, it will resize the key symbols table to 0 but leave the key actions unchanged. If the same function is later called with a non-zero value of groups, this will cause a buffer overflow because the key actions are of the wrong size.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat Tigervnc X.org

Products

Enterprise Linux Rhel Aus Rhel E4s and 6 more

CVE-2025-26596

Xorg: xwayland: heap overflow in xkbwritekeysyms()

A heap overflow flaw was found in X.Org and Xwayland. The computation of the length in XkbSizeKeySyms() differs from what is written in XkbWriteKeySyms(), which may lead to a heap-based buffer overflow.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat Tigervnc X.org

Products

Enterprise Linux Rhel Aus Rhel E4s and 6 more

CVE-2025-26595

Xorg: xwayland: buffer overflow in xkbvmodmasktext()

A buffer overflow flaw was found in X.Org and Xwayland. The code in XkbVModMaskText() allocates a fixed-sized buffer on the stack and copies the names of the virtual modifiers to that buffer. The code fails to check the bounds of the buffer and would copy the data regardless of the size.

CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Vendors

Redhat Tigervnc X.org

Products

Enterprise Linux Rhel Aus Rhel E4s and 6 more