Is CVE-2026-96423 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-96423 being exploited in the wild.

How severe is CVE-2026-96423?

Medium severity, with a CVSS score of 5.5, published 29 September 2026.

Which products and versions are affected?

Wireshark Foundation Wireshark 4.6.0 to 4.6.8, 4.4.0 to 4.4.18.

Is there a fix for CVE-2026-96423?

A patch was published on 2026-09-29: fixed in 4.6.9 and 4.4.19 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-96423 attacked?

It is attacked with local access, in a software library.

Am I affected by CVE-2026-96423?

Check whether you run Wireshark Foundation Wireshark 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.

CVE-2026-96423: Wireshark X11 dissector out-of-bounds heap read

CVE-2026-96423 · Severity: medium · CVSS 5.5 · Published 2026-09-29

The X11 protocol dissector in Wireshark—a tool used to analyze network traffic—contains a memory access vulnerability that can crash the application or disclose heap memory contents. An attacker can craft a malicious network capture file that triggers an out-of-bounds read when opened in Wireshark, leading to denial of service or information leakage without requiring any user interaction beyond opening the file.

Technologies: Wireshark Foundation Wireshark. Vendors: Wireshark Foundation.

Quick answers

Is CVE-2026-96423 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-96423 being exploited in the wild.
How severe is CVE-2026-96423?: Medium severity, with a CVSS score of 5.5, published 29 September 2026.
Which products and versions are affected?: Wireshark Foundation Wireshark 4.6.0 to 4.6.8, 4.4.0 to 4.4.18.
Is there a fix for CVE-2026-96423?: A patch was published on 2026-09-29: fixed in 4.6.9 and 4.4.19 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-96423 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2026-96423?: Check whether you run Wireshark Foundation Wireshark 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

The X11 dissector maintains a per-conversation cache of keysym arrays, each allocated with a message-specific width, but tracks only a single scalar width value. The X_ChangeKeyboardMapping request updates cache entries independently without updating the scalar, while X_GetKeyboardMapping reply updates only the scalar, causing divergence. When KeyPress/KeyRelease events are dissected, the keycode2keysymString() function indexes cached arrays using the out-of-sync scalar width without bounds checking, resulting in heap buffer over-read from narrower arrays.

Affected products

Wireshark Foundation Wireshark 4.6.0 to 4.6.8, 4.4.0 to 4.4.18

Timeline

2026-09-23: disclosed
2026-09-29: advisory: wnpa-sec-2026-108 published
2026-09-29: patched: fixed in 4.6.9 and 4.4.19

References

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