CVE-2026-33999

high

Published 2026-04-27 · Modified 2026-06-02

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CVSS v3

7.8

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v4 NEW

—

not yet in upstream

VIR risk

7.8

Description

A flaw was found in the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violations and potentially a denial of service (DoS) or other severe impacts.

Predictions

Exploit likelihood

75%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

SUSE Affected 1 release

Version	Status	Fixed in
—	Affected	—

Debian Mixed 5 releases

Version	Status	Fixed in
trixie	Fixed	`2:21.1.16-1.3+deb13u2`
sid	Fixed	`2:21.1.22-1`
forky	Fixed	`2:21.1.22-1`
bullseye	Affected	—
bookworm	Fixed	`2:21.1.7-3+deb12u12`

AlmaLinux Fixed 1 release

Version	Status	Fixed in
9	Fixed	`tigervnc-license-1.15.0-6.el9_7.1.noarch.rpm`

Red Hat Fixed 2 releases

Version	Status	Fixed in
9	Fixed	—
8	Fixed	—

Rocky Linux Fixed 1 release

Version	Status	Fixed in
9	Fixed	—

References

CWEs

CWE-191

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.