A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized…
redhat·CWE-121·Published 2026-06-05
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.
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.
| Version | Type | Source | Base | Exp | Impact | Vector |
|---|---|---|---|---|---|---|
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | NVD | 7.8 | 1.8 | 5.9 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Primary | cve.org | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Secondary | ENISA EUVD | 7.8 | — | — | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Secondary | NVD | 7.8 | 1.8 | 5.9 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | Secondary | NVD | 7.8 | 1.8 | 5.9 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |