Out-of-Bounds Read Vulnerability in GNU Gatekeeper by Willamowius
CVE-2026-121625

6.3MEDIUM

Key Information:

Vendor

Willamowius

Status
Gnugk
Vendor
CVE Published:
3 November 2026

What is CVE-2026-121625?

GNU Gatekeeper versions prior to 5.16 contain a vulnerability that exposes the system to out-of-bounds read attacks. This occurs in the ParseRTCP() function within ProxyChannel.cxx. By sending malformed RTCP SDES items that do not include a NUL byte to the media proxy port during proxied H.323 calls (with EnableRTCPStats enabled), an attacker can manipulate memory access, potentially allowing them to read sensitive data from heap memory beyond the intended limits. The vulnerability may lead to service disruptions, including crashes in the gatekeeper service, necessitating prompt updates to secure affected installations.

Affected Version(s)

gnugk 0 < 5.16

References

https://github.com/willamowius/gnugk/commit/e8939d03b0b2e...
patch
https://github.com/willamowius/gnugk/releases/tag/v5_16
release-notes
https://github.com/willamowius/gnugk/blob/v5_15/ProxyChan...
technical-description

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Tristan Madani (Talence Security)
Jan Willamowius
.