SignalWire FreeSWITCH up to 1.11.1 mod_rtmp rtmp_rtmp2rtpH264 integer underflow

Summaryinfo

A vulnerability classified as critical was found in SignalWire FreeSWITCH up to 1.11.1. Impacted is the function rtmp_rtmp2rtpH264 of the component mod_rtmp. The manipulation results in integer underflow. This vulnerability is cataloged as CVE-2026-116568. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in SignalWire FreeSWITCH up to 1.11.1. Affected is the function rtmp_rtmp2rtpH264 of the component mod_rtmp. The manipulation with an unknown input leads to a integer underflow vulnerability. CWE is classifying the issue as CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. This is going to have an impact on availability. CVE summarizes:

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. Prior to 1.11.2, rtmp_rtmp2rtpH264() trusted the length prefix of each inbound H.264 NAL unit without checking it against the bytes remaining in the RTMP message. An oversized declared unit underflowed the unsigned remaining-byte counter and advanced the parser beyond its receive buffer, where the next length-prefix read could crash the process. The flaw affects deployments that build and load mod_rtmp and accept video call sessions, commonly on TCP port 1935; placing the call requires a directory login where auth-calls is true, while no credentials are required where auth-calls is absent or false. A remote client can terminate FreeSWITCH and every active call, but the defect supplies no write primitive and memory disclosure has not been demonstrated. This issue is fixed in version 1.11.2.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-116568 since 10/26/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit.

Upgrading to version 1.11.2 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• SignalWire

Name

• FreeSWITCH

Version

• 1.11.0
• 1.11.1

Website

• Product: https://github.com/signalwire/freeswitch/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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