Xorg: xwayland: use-after-free in syncinittrigger() (CVE-2025-26601)

Why this deserves its current priority

CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps xserver (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
xservergeneric	>=0 <21.1.16 \|\| >=22.0.0 <24.1.6	21.1.16, 24.1.6

Recommended response

Check inventory. Check lockfiles and deployed manifests for xserver.
Review the reported fix. Source-reported workaround: Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Evidence timeline and material changes

Published upstream
Feb 25, 2025
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Jun 29, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jun 25, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.

Xorg: xwayland: use-after-free in syncinittrigger()CVE-2025-26601