UBUNTU-CVE-2026-121625: Medium severity ubuntu/gnugk vulnerability

Published Nov 3, 2026

Updated

GNU Gatekeeper (gnugk) before 5.16 contains an out-of-bounds read vulnerability in ParseRTCP() in ProxyChannel.cxx that allows remote RTP peers to read heap memory past received packets. Attackers can send RTCP SDES items lacking a NUL byte to the media proxy port during proxied H.323 calls with EnableRTCPStats enabled, crashing the gatekeeper.

Affected Software

2 affected components

ubuntu/gnugk*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade GNU Gatekeeper (gnugk) to a version that resolves this vulnerability.
Fixed in 5.16

Event History

Nov 3, 2026

CVE Published

via OSV·06:17 PM

Data Sourced

via OSV·06:17 PM

DescriptionSeverityAffected Software

Frequently Asked Questions

Which deployments are exposed?

Exposure requires GNU Gatekeeper to handle proxied H.323 calls with EnableRTCPStats enabled. The crafted traffic is sent to the media proxy port by a remote RTP peer.

What must an attacker be able to do?

An attacker needs to act as a remote RTP peer and send an RTCP SDES item that lacks a NUL byte to the media proxy port during a proxied H.323 call. No privileges or user interaction are required according to the supplied vector.

What is the practical impact?

The out-of-bounds read can crash the gatekeeper, causing an availability impact. The supplied severity vector indicates no confidentiality or integrity impact.

What can be done if an update cannot be applied immediately?

Disable EnableRTCPStats where operationally feasible, since the vulnerable path requires that setting to be enabled. Updating gnugk to version 5.16 or later removes exposure to versions identified as affected.

UBUNTU-CVE-2026-121625: Medium severity ubuntu/gnugk vulnerability

Affected Software

Remediation

Event History

Frequently Asked Questions

Which deployments are exposed?

What must an attacker be able to do?

What is the practical impact?

What can be done if an update cannot be applied immediately?

Company

Resources

Contact

Frequently Asked Questions

Which deployments are exposed?

What must an attacker be able to do?

What is the practical impact?

What can be done if an update cannot be applied immediately?