CVE-2026-34001: xorg-server Expired Pointer Dereference
Vulnerability summary
CVE-2026-34001 is a high (CVSS 7.8) Expired Pointer Dereference vulnerability in xorg-server. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 8.1% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 48 · Related 12Timeline
- 23-04-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- NVDNIST7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.19%
Chance of exploitation in the next 30 days
Percentile
8%
Versus all other CVEs
30-day change
-0.07 pp
From 0.26% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu4 products
- xorg-serverAll versions (No fix recorded)
- xorg-server-hwe-16.04All versions (No fix recorded)
- xorg-server-hwe-18.04All versions (No fix recorded)
- xwaylandAll versions (No fix recorded)
Debian2 products
- xorg-server< 2:21.1.7-3+deb12u12 | < 2:21.1.16-1.3+deb13u2 | < 2:21.1.22-1
- xwaylandAll versions (No fix recorded) | < 2:24.1.10-1
2 vendors · 6 products
