Quick answers
- Is CVE-2026-88806 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-88806 being exploited in the wild.
- How severe is CVE-2026-88806?
- High severity, with a CVSS score of 7.5, published 21 September 2026.
- Which products and versions are affected?
- X.Org libX11 before 1.8.14.
- Is there a fix for CVE-2026-88806?
- A patch was published on 2026-09-18: Fix merged in libX11 via merge request 309 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-88806 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-88806?
- Check whether you run X.Org libX11 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A buffer overflow exists in libX11 before 1.8.14 in the _XkbReadKeyActions function where a malicious server can send a XkbGetMap reply with firstKeyAct + nKeyActs exceeding max_keycode + 1, causing out-of-bounds writes to the key_sym_map array. The vulnerability requires network access to a running X server and no user interaction beyond normal X client operation. The fix adds range validation to ensure keysym indices stay within bounds.
Affected products
- X.Org libX11 before 1.8.14
Timeline
- 2026-09-21: disclosed: CVE-2026-88806 published
- 2026-09-18: patched: Fix merged in libX11 via merge request 309