Stack-based Buffer Overflow Affecting xorg-server package, versions <2:1.20.11-1+deb11u18


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.16% (6th percentile)

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  • Snyk IDSNYK-DEBIAN11-XORGSERVER-17192525
  • published5 Jun 2026
  • disclosed5 Jun 2026

Introduced: 5 Jun 2026

CVE-2026-50258  (opens in a new tab)
CWE-121  (opens in a new tab)

How to fix?

Upgrade Debian:11 xorg-server to version 2:1.20.11-1+deb11u18 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xorg-server package and not the xorg-server package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.

References

CVSS Base Scores

version 3.1