# CVE-2026-5402: Wireshark TLS protocol dissector heap overflow

Source: https://junglewise.ai/threats/cve-2026-5402-wireshark-tls-protocol-dissector-heap-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-30. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-5402 · Severity: high · CVSS 8.8 · Published 2026-04-30

Wireshark, a widely used network protocol analyzer, is vulnerable to a flaw in how it processes encrypted web traffic (TLS). An attacker can exploit this by sending a malicious network packet or tricking a user into opening a specially crafted capture file. This could lead to the application crashing or, in some cases, allow the attacker to execute unauthorized code on the user's system.

Technologies: [Wireshark](https://junglewise.ai/threats/technologies/wireshark). Vendors: [Wireshark](https://junglewise.ai/threats/vendors/wireshark).

## Quick answers

**Is CVE-2026-5402 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5402 being exploited in the wild.

**How severe is CVE-2026-5402?** High severity, with a CVSS score of 8.8, published 30 April 2026.

**Which products and versions are affected?** Wireshark Foundation Wireshark 4.6.0 to 4.6.4.

**Is there a fix for CVE-2026-5402?** A patch was published on 2026-04-30: Wireshark 4.6.5 released to address the issue Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-5402 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-5402?** Check whether you run Wireshark. 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 heap-based buffer overflow exists in Wireshark's TLS Encrypted Client Hello (ECH) transcript reconstruction code. The vulnerability is caused by integer truncation and unsigned underflow issues during the processing of 'ech_outer_extensions'. Specifically, truncation in the extensions loop allows an attacker to write controlled data past the bounds of a heap-allocated buffer. An attacker can trigger this by injecting a malformed TLS ClientHello packet into live traffic being captured or by providing a crafted .pcapng file for analysis. This can result in a crash (DoS) or arbitrary code execution. The issue is resolved in Wireshark version 4.6.5.

## Affected products

- Wireshark Foundation Wireshark 4.6.0 to 4.6.4

## Timeline

- 2026-04-29: advisory: Wireshark published wnpa-sec-2026-14
- 2026-04-30: disclosed: CVE-2026-5402 published to NVD
- 2026-04-30: patched: Wireshark 4.6.5 released to address the issue

## References

- [https://gitlab.com/wireshark/wireshark/-/issues/21090](https://gitlab.com/wireshark/wireshark/-/issues/21090)
- [https://www.wireshark.org/security/wnpa-sec-2026-14.html](https://www.wireshark.org/security/wnpa-sec-2026-14.html)
- [https://access.redhat.com/security/cve/CVE-2026-5402](https://access.redhat.com/security/cve/CVE-2026-5402)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2464038](https://bugzilla.redhat.com/show_bug.cgi?id=2464038)
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5402.json](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5402.json)

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