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CVE-2026-50261

high

A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter().

Vendor / product: X.org — x server

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
7.8
7.8 (CVSS v3.1)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity source: NVD CVSS v3.1 (secalert@redhat.com)
Timeline (UTC)
Published: 2026-06-05 12:16
Modified: 2026-11-04 23:17
NVD status: Modified
Last synced 1 hour ago
Verified against the source API 2026-11-04 23:38 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

x.org / x_server <21.1.23
x.org / xwayland <24.1.12
redhat / enterprise_linux 7.0, 8.0, 9.0, 10.0

Weakness classification (CWE)

CWE-416

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://lists.x.org/archives/xorg-announce/2026-June/003702.html
Patch / mitigation: https://gitlab.freedesktop.org/xorg/xserver/-/commit/bdd7bf57af208b1ddf57d4683d67104443b44812

References

Data sources

NVD CVE API 2.0 — fetched 2026-11-04 23:38 UTC · record ↗

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Related CVEs

CVE-2026-50264CVE-2026-50260CVE-2026-50259CVE-2026-50258CVE-2026-50257