| Name | CVE-2026-34001 |
| Description | 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| xorg-server (PTS) | bullseye | 2:1.20.11-1+deb11u13 | vulnerable |
| bullseye (security) | 2:1.20.11-1+deb11u17 | vulnerable |
| bookworm, bookworm (security) | 2:21.1.7-3+deb12u11 | vulnerable |
| trixie (security), trixie | 2:21.1.16-1.3+deb13u1 | vulnerable |
| forky | 2:21.1.21-1 | vulnerable |
| sid | 2:21.1.22-1 | fixed |
| xwayland (PTS) | bookworm | 2:22.1.9-1 | vulnerable |
| trixie | 2:24.1.6-1 | vulnerable |
| forky | 2:24.1.10-1 | fixed |
| sid | 2:24.1.11-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|
| xorg-server | source | (unstable) | 2:21.1.22-1 | | | |
| xwayland | source | (unstable) | 2:24.1.10-1 | | | |
Notes
[trixie] - xorg-server <no-dsa> (Minor issue, will be fixed via point release)
[bookworm] - xorg-server <no-dsa> (Minor issue, will be fixed via point release)
[bullseye] - xorg-server <postponed> (Minor issue)
[trixie] - xwayland <ignored> (Minor issue; Xwayland shouldn't be running as root)
[bookworm] - xwayland <ignored> (Minor issue; Xwayland shouldn't be running as root)
https://lists.x.org/archives/xorg-announce/2026-April/003677.html
Fixed by: https://gitlab.freedesktop.org/xorg/xserver/-/commit/f19ab94ba9c891d801231654267556dc7f32b5e0