# CVE-2026-94283: libX11 out-of-bounds read in XIM attribute parser

Source: https://junglewise.ai/threats/cve-2026-94283-an-out-of-bounds-read-vulnerability-in-libx11-s-xim-x-input  
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-2026-94283 · Severity: medium · CVSS 6.5 · Published 2026-09-28

libX11 is a core library that handles communication between X11 graphical applications and X servers. A malicious X server can exploit an out-of-bounds read vulnerability in the XIM (X Input Method) attribute parser to crash connected X client applications, potentially disrupting user sessions.

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

## Quick answers

**Is CVE-2026-94283 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-94283 being exploited in the wild.

**How severe is CVE-2026-94283?** Medium severity, with a CVSS score of 6.5, published 28 September 2026.

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

**Is there a fix for CVE-2026-94283?** A patch was published on 2026-09-23: Merge request #310 with fixes merged upstream Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-94283 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-94283?** 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 flaw exists in libX11's XIM attribute parser (imRmAttr.c and imDefIm.c) due to insufficient bounds checking when parsing XIM protocol messages from X servers. The vulnerability is reachable by any malicious X server without authentication. Exploitation results in a crash of the connected X client; a fix was merged into the upstream repository in September 2026.

## Affected products

- X.Org libX11 before 1.8.14

## Timeline

- 2026-09-28: disclosed: CVE-2026-94283 published
- 2026-09-23: patched: Merge request #310 with fixes merged upstream

## References

- [https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/310/diffs?commit_id=42d0303f243002a9856c76060569a61893c670dd](https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/310/diffs?commit_id=42d0303f243002a9856c76060569a61893c670dd)

## Related threats

- [libX11 out-of-bounds read in XIM trigger-key registration parser](https://junglewise.ai/threats/cve-2026-94284-an-out-of-bounds-read-vulnerability-in-libx11-s-xim-trigger-key)
- [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)