id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc
23400	xwayland-24.1.12	Douglas R. Reno	SecurityAdvisory	"New point version

This contains security fixes, but first: the release announcement...

{{{
This release contains the fixes for the issues reported in today's 
security advisory:

https://lists.x.org/archives/xorg-announce/2026-June/003702.html

  - Font Alias Stack-based Buffer Overflow
  - XSYNC Use-After-Free in miSyncDestroyFence()
  - XKB Key Types Stack-based Buffer Overflow
  - XKB SetMap Request Stack-based Buffer Overflow
  - XSYNC Use-After-Free in FreeCounter()
  - XSYNC Use-After-Free in SyncChangeCounter()
  - GLX ChangeDrawableAttributes Out-Of-Bounds Read/Write
  - CreateSaverWindow Use-After-Free Information Disclosure

Additionally, it contains a number of other various fixes from the 
stable xwayland-24.1 branch.

Mikhail Dmitrichenko (2):
      xkb: fix incorrect size check when growing doodads in a section
      xkb: fix potential buff overflow in XkbVModIndexText for XkbCFile format

Peter Hutterer (15):
      Xi: add missing gesture grab type checks in ProcXIPassiveUngrabDevice
      xkb: Fix out-of-bounds array access in _CheckSetShapes()
      xkb: Fix off-by-one in color index validation in _CheckSetGeom()
      xkb: Fix off-by-one and NULL dereferences in _CheckSetOverlay()
      xkb: Add bounds check for action data in CheckKeyActions()
      present: actually return the created notifies
      glx: reject negative size in FeedbackBuffer and SelectBuffer requests
      sync: fix deletion of counters and fences
      sync: restart trigger list iteration in SyncChangeCounter after TriggerFired
      xkb: reject key types with num_levels exceeding XkbMaxShiftLevel
      xkb: clamp nMaps to mapWidths buffer size in CheckKeyTypes
      glx: fix reversed length check in ChangeDrawableAttributes
      saver: re-fetch screen private after CheckScreenPrivate in CreateSaverWindow
      dix: increase XLFDMAXFONTNAMELEN to match libXfont2's MAXFONTNAMELEN
      Bump version to 24.1.11

git tag: xwayland-24.1.12
}}}

The security announcement:

{{{
=======================================================================
X.Org Security Advisory: June 2, 2026 

Issues in X.Org X server prior to 21.1.23 and Xwayland prior to 24.1.12
=======================================================================

Multiple issues have been found in the X server and Xwayland 
implementations published by X.Org for which we are releasing security 
fixes for in xorg-server-21.1.23 and xwayland-24.1.12.

Note that CVEs have been requested for these issues but did not get 
assigned in time for this disclosure.

* Font Alias Stack-based Buffer Overflow

    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.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/bb5158f962dc935e58ef8b4b5fcb31be201a6e07
    Found by: Anonymous working with TrendAI Zero Day Initiative.
              (ZDI-CAN-30136)

* XSYNC Use-After-Free 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.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b
    Found by: Anonymous working with TrendAI Zero Day Initiative.
              (ZDI-CAN-30159)

* XKB Key Types Stack-based Buffer Overflow

    The X server has multiple stack buffers that are 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 three separate
    stack overflows.

    This is caused by an incomplete fix of CVE-2025-26597.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/543e108516428fc8c3bea91d6563ad266f9a801e
    Found by: Anonymous working with TrendAI Zero Day Initiative.
              (ZDI-CAN-30160)

* XKB SetMap Request Stack-based Buffer Overflow

    _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.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/867b59b33bee669cb412f1314e47c52eacf6e00b
    Found by: Anonymous working with TrendAI Zero Day Initiative.
              (ZDI-CAN-30161)

* XSYNC Use-After-Free 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.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b
    Found by: Anonymous working with TrendAI Zero Day Initiative.
              (ZDI-CAN-30163)

* XSYNC Use-After-Free 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.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/bdd7bf57af208b1ddf57d4683d67104443b44812
    Found by: Anonymous working with TrendAI Zero Day Initiative.
              (ZDI-CAN-30164)

* GLX ChangeDrawableAttributes Out-Of-Bounds Read/Write

    A wrong size validation check in __glXDisp_ChangeDrawableAttributes()
    can read (or write) a client-controlled number of bytes, exceeding
    the request buffer.

    The write path requires byte-swapped clients which is disabled by
    default.

    The read can lead to information disclosure, the write can be used
    to crash the server, or for privilege escalation if the X server runs
    as root.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/6d459e4daf715bea8abdafa8fb130be2f8a1d145
    Found by: Anonymous working with TrendAI Zero Day Initiative.
              (ZDI-CAN-30165)

* CreateSaverWindow Use-After-Free Information Disclosure

    A client can trigger a use-after-free read after changing window
    attributes and forcing the screen saver. This can lead to information
    disclosure.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/ecc634f1b2f7aa473d3a267eada98c4918bf9e05
    Found by: Anonymous working with TrendAI Zero Day Initiative.
              (ZDI-CAN-30168)

* DRI2 DRIGetBuffers/DRIGetBuffersWithFormat Out-Of-Bounds Write

    A client that requests multiple DRI2BufferBackLeft attachments and one
    DRI2BufferFrontLeft can trigger an out-of-bounds heap write.

    Fixed in: xorg-server-21.1.23 and xwayland-24.1.12
    Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/339c279514326134b0878fc23ce6e9520440ce7f
         https://gitlab.freedesktop.org/xorg/xserver/-/commit/b7aa65cc3bb11b792ce2a3f511ba9b863acb11c8
    Found by: Peter Hutterer, Red Hat.
}}}"	enhancement	closed	elevated	98-Security	BOOK	git	medium	fixed