Stack-based Buffer Overflow Affecting xorg-x11-server-Xnest package, versions <0:1.20.11-34.el9_8.2


Severity

Recommended
0.0
high
0
10

Based on AlmaLinux security rating.

Threat Intelligence

EPSS
0.16% (6th percentile)

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  • Snyk IDSNYK-ALMALINUX9-XORGX11SERVERXNEST-17807698
  • published3 Jul 2026
  • disclosed25 Jun 2026

Introduced: 25 Jun 2026

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

How to fix?

Upgrade AlmaLinux:9 xorg-x11-server-Xnest to version 0:1.20.11-34.el9_8.2 or higher.
This issue was patched in ALSA-2026:26610.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xorg-x11-server-Xnest package and not the xorg-x11-server-Xnest package as distributed by AlmaLinux. See How to fix? for AlmaLinux:9 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