CVSS 3.1
7.8 highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCVE-2026-50258
High (7.8). EPSS 0.2% chance of exploitation in the next 30 days.
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.
Severity
- EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 5% of CVEs (scores of 2026-10-31)
- CWE
- CWE-121
- Published
- Modified
- Record from
- the NVD, synced
Affected
- redhat:enterprise_linux
- x.org:x_server
- x.org:xwayland