# CVE-2026-94284: libX11 out-of-bounds read in XIM trigger-key registration parser

Source: https://junglewise.ai/threats/cve-2026-94284-an-out-of-bounds-read-vulnerability-in-libx11-s-xim-trigger-key  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-28. Updated: 2026-09-28  
License: CC BY 4.0 with a link back

CVE-2026-94284 · Severity: medium · CVSS 5.5 · Published 2026-09-28

libX11 is a core library that handles communication between X client applications and X servers on Unix-like systems. A malicious X server can trigger an out-of-bounds memory read in the trigger-key registration parser, causing X client applications to crash and resulting in denial of service.

Technologies: [X.Org libX11](https://junglewise.ai/threats/technologies/libx11). Vendors: [X.Org](https://junglewise.ai/threats/vendors/x-org).

## Quick answers

**Is CVE-2026-94284 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-94284 being exploited in the wild.

**How severe is CVE-2026-94284?** Medium severity, with a CVSS score of 5.5, published 28 September 2026.

**Which products and versions are affected?** X.Org libX11 before 1.8.14.

**Is there a fix for CVE-2026-94284?** A patch was published on 2026-09-23. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-94284 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-94284?** 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

An out-of-bounds read vulnerability exists in the _XimRegisterTriggerkey() function in libX11's XIM (X Input Method) implementation when parsing trigger-key registration messages. The vulnerability stems from insufficient bounds checking on untrusted data received from X servers. An attacker controlling an X server can send a crafted message to crash connected X clients.

## Affected products

- X.Org libX11 before 1.8.14

## Timeline

- 2026-09-28: disclosed
- 2026-09-23: patched

## References

- [https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/310/diffs?commit_id=1b7904002d212eed40949ccf4e8e7156f9fec0e2](https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/310/diffs?commit_id=1b7904002d212eed40949ccf4e8e7156f9fec0e2)

## Related threats

- [libX11 out-of-bounds read in XIM attribute parser](https://junglewise.ai/threats/cve-2026-94283-an-out-of-bounds-read-vulnerability-in-libx11-s-xim-x-input)
- [libX11 buffer overflow in XkbGetMap key_sym_map handling](https://junglewise.ai/threats/cve-2026-88806-a-malicious-x-server-could-exploit-a-buffer-overflow-in-libx11)