CVE-2026-50258
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.
- Affected products
- Rocky Linux, X.Org Server, Xwayland
- X.org X Server
- < 21.1.23
- X.org Xwayland
- < 24.1.12
- Redhat Enterprise Linux
- = 7.0, 8.0, 9.0, 10.0
- CVSS 3.1
- 7.8 HIGH
- EPSS
- 0.2% (6th percentile)
- Weakness
- CWE-121
- NVD status
- Modified
- Published
- 2026-06-05
CVE-2026-50258 at NVD
No indexed exploits for CVE-2026-50258 yet
Our index is partial: it proves presence, never absence
No exploit for CVE-2026-50258 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.