# CVE-2026-76929: Wireshark pcapng file parser heap out-of-bounds read

Source: https://junglewise.ai/threats/cve-2026-76929-wireshark-pcapng-file-parser-heap-out-of-bounds-read  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-19. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-76929 · Severity: medium · CVSS 4.7 · Published 2026-08-19

Wireshark is a network traffic analysis tool used to inspect and troubleshoot network communications. A flaw in its pcapng file parser can be triggered by opening a malformed packet capture file, causing the application to crash and denying service to analysts who depend on it for network diagnostics. An attacker could distribute a crafted capture file to cause denial of service.

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

## Quick answers

**Is CVE-2026-76929 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-76929 being exploited in the wild.

**How severe is CVE-2026-76929?** Medium severity, with a CVSS score of 4.7, published 19 August 2026.

**Which products and versions are affected?** Wireshark 4.6.0 to 4.6.7, 4.4.0 to 4.4.17.

**Is there a fix for CVE-2026-76929?** A patch was published on 2026-08-19: Fixed in Wireshark 4.6.8, 4.4.18 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-76929 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-76929?** Check whether you run 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 vulnerability is a heap-based out-of-bounds read in the Netflix pcapng TCPINFO custom option parser (wiretap/pcapng-netflix-custom.c). The parser validates only a 4-byte subtype field but then unconditionally performs two 8-byte timestamp reads without checking payload length. A malformed pcapng custom block with an empty TCPINFO payload triggers an 8-byte out-of-bounds read, causing a crash via AddressSanitizer detection or direct heap corruption. No authentication or user interaction is required beyond opening the malicious file; the crash occurs during initial packet capture parsing before any dissection. Patches are available in Wireshark 4.6.8 and 4.4.18+, which add length validation before the timestamp reads.

## Affected products

- Wireshark Wireshark 4.6.0 to 4.6.7, 4.4.0 to 4.4.17

## Timeline

- 2026-08-12: disclosed
- 2026-08-19: patched: Fixed in Wireshark 4.6.8, 4.4.18

## References

- [https://gitlab.com/wireshark/wireshark/-/work_items/21460](https://gitlab.com/wireshark/wireshark/-/work_items/21460)
- [https://www.wireshark.org/security/wnpa-sec-2026-84.html](https://www.wireshark.org/security/wnpa-sec-2026-84.html)

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