X.Org Server XkbResizeKeySyms overflow allows local privilege escalation
ZDI rates CVE-2026-50258 at 7.8 and says low-privileged code is required first.
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CVE-2026-50258
- CVSS 3.1
- 7.8 high
- EPSS
- <1%p6
- Published
- ·
- Modified
Description · NVD
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.
- Products
- x server, xwayland, enterprise linux
- Weakness
- CWE-121
- Vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H