SignalWire FreeSWITCH up to 1.11.1 mod_rtmp rtmp_handle_control stack-based overflow

Summaryinfo

A vulnerability, which was classified as problematic, was found in SignalWire FreeSWITCH up to 1.11.1. The impacted element is the function rtmp_handle_control of the component mod_rtmp. Such manipulation leads to stack-based overflow. This vulnerability is documented as CVE-2026-116567. The attack can be executed remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in SignalWire FreeSWITCH up to 1.11.1 and classified as problematic. Affected by this issue is the function rtmp_handle_control of the component mod_rtmp. The manipulation with an unknown input leads to a stack-based overflow vulnerability. Using CWE to declare the problem leads to CWE-121. The product writes past the end of a buffer that was allocated on the stack. Impacted is 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_handle_control() rendered an RTMP user-control message into a 200-byte stack buffer using an unbounded sprintf loop controlled by the wire message length. A body of roughly 70 bytes or more overflowed the stack before any RTMP login, because the handshake authenticates neither side. The flaw affects deployments that build and load mod_rtmp, which is disabled in the stock build and configuration but commonly exposes a listener on TCP port 1935 when enabled. One unauthenticated message can crash FreeSWITCH and end every active call; the constrained ASCII hex output has not yielded control-flow hijacking. This issue is fixed in version 1.11.2.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-116567 since 10/26/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 1.11.2 eliminates this vulnerability.

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Productinfo

Vendor

• SignalWire

Name

• FreeSWITCH

Version

• 1.11.0
• 1.11.1

Website

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

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