# CVE-2026-5405: Wireshark heap overflow in RDP dissector

Source: https://junglewise.ai/threats/cve-2026-5405-wireshark-heap-overflow-in-rdp-dissector  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-01. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-5405 · Severity: high · CVSS 7.8 · Published 2026-05-01

Wireshark, a widely used network protocol analyzer, is vulnerable to a flaw in its Remote Desktop Protocol (RDP) analysis component. An attacker can exploit this by sending a specially crafted network packet or tricking a user into opening a malicious capture file. This could result in the application crashing or potentially allow the attacker to execute unauthorized code on the system.

## Quick answers

**Is CVE-2026-5405 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5405 being exploited in the wild.

**How severe is CVE-2026-5405?** High severity, with a CVSS score of 7.8, published 1 May 2026.

**Which products and versions are affected?** Wireshark Foundation Wireshark 4.6.0 to 4.6.4, 4.4.0 to 4.4.14.

**Is there a fix for CVE-2026-5405?** A patch was published on 2026-05-26: Red Hat released security updates for RHEL 10 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-5405 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-5405?** Check whether anything you run is named in the advisory. 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 the RDP dissector's ZGFX decompression logic, specifically within the rdp8_decompress_segment() function in epan/tvbuff_rdp.c. The vulnerability is caused by a lack of bounds checking on the uncompressed path when copying attacker-controlled data into a fixed 65,536-byte outputSegment buffer. An attacker can trigger this overflow by providing a ZGFX segment larger than the buffer size. This is reachable through the standard RDP dissection chain (TCP 3389) via the Microsoft::Windows::RDS::Graphics dynamic channel. Successful exploitation can lead to a crash (SIGSEGV) or arbitrary code execution. Patches are available in Wireshark versions 4.6.5 and 4.4.15.

## Affected products

- Wireshark Foundation Wireshark 4.6.0 to 4.6.4, 4.4.0 to 4.4.14

## Timeline

- 2026-04-29: advisory: Wireshark published wnpa-sec-2026-17
- 2026-05-01: disclosed: NVD publication date
- 2026-05-26: patched: Red Hat released security updates for RHEL 10

## References

- [https://gitlab.com/wireshark/wireshark/-/issues/21105](https://gitlab.com/wireshark/wireshark/-/issues/21105)
- [https://www.wireshark.org/security/wnpa-sec-2026-17.html](https://www.wireshark.org/security/wnpa-sec-2026-17.html)
- [https://access.redhat.com/errata/RHSA-2026:20600](https://access.redhat.com/errata/RHSA-2026:20600)
- [https://access.redhat.com/errata/RHSA-2026:26182](https://access.redhat.com/errata/RHSA-2026:26182)
- [https://access.redhat.com/security/cve/CVE-2026-5405](https://access.redhat.com/security/cve/CVE-2026-5405)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2464273](https://bugzilla.redhat.com/show_bug.cgi?id=2464273)
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5405.json](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5405.json)