# CVE-2026-116567: FreeSWITCH stack buffer overflow in RTMP control message handler

Source: https://junglewise.ai/threats/cve-2026-116567-freeswitch-is-a-software-defined-telecom-stack-enabling-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-05. Updated: 2026-11-05  
License: CC BY 4.0 with a link back

CVE-2026-116567 · Severity: high · CVSS 7.5 · Published 2026-11-05

FreeSWITCH is a telecommunications platform that processes voice, video, and messaging calls. The RTMP protocol module contains a vulnerability where an unauthenticated attacker can send a specially crafted message that crashes the server, terminating all active calls. This vulnerability requires the optional RTMP module to be enabled, which is not part of the default installation but is commonly deployed on systems that handle real-time media streaming.

Technologies: [SignalWire FreeSWITCH](https://junglewise.ai/threats/technologies/freeswitch). Vendors: [SignalWire](https://junglewise.ai/threats/vendors/signalwire).

## Quick answers

**Is CVE-2026-116567 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-116567 being exploited in the wild.

**How severe is CVE-2026-116567?** High severity, with a CVSS score of 7.5, published 5 November 2026.

**Which products and versions are affected?** SignalWire FreeSWITCH before 1.11.2.

**Is there a fix for CVE-2026-116567?** Yes: fixed in FreeSWITCH 1.11.2. Until then: Disable the mod_rtmp module if RTMP functionality is not required. Restrict network access to port 1935 to trusted clients only, since the vulnerability is triggered before authentication. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-116567 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-116567?** Check whether you run SignalWire FreeSWITCH at an affected version. 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.

## How to fix

- Fixed in FreeSWITCH 1.11.2

Disable the mod_rtmp module if RTMP functionality is not required. Restrict network access to port 1935 to trusted clients only, since the vulnerability is triggered before authentication.

## Technical details

The rtmp_handle_control() function in mod_rtmp formats untrusted wire message data into a fixed 200-byte stack buffer using unbounded sprintf in a loop controlled by the message length field, before any authentication occurs. An attacker can send a ~70 byte or larger RTMP user-control message to trigger a stack buffer overflow via TCP port 1935. While the vulnerability is limited to ASCII hex output and does not enable code execution, the resulting memory corruption crashes the process and terminates all active calls.

## Affected products

- SignalWire FreeSWITCH before 1.11.2

## Timeline

- 2026-11-05: advisory

## References

- [https://github.com/signalwire/freeswitch/commit/fc0db829b87d1a5a3043e355b4294c41851b13c6](https://github.com/signalwire/freeswitch/commit/fc0db829b87d1a5a3043e355b4294c41851b13c6)
- [https://github.com/signalwire/freeswitch/releases/tag/v1.11.2](https://github.com/signalwire/freeswitch/releases/tag/v1.11.2)

## Related threats

- [FreeSWITCH ICE integrity validation bypass](https://junglewise.ai/threats/cve-2026-116790-freeswitch-is-a-software-defined-telecom-stack-enabling-the)
- [FreeSWITCH DTLS fingerprint validation bypass in server role](https://junglewise.ai/threats/cve-2026-116789-freeswitch-is-a-software-defined-telecom-stack-enabling-the)
- [FreeSWITCH integer underflow in XML decode](https://junglewise.ai/threats/cve-2026-116788-freeswitch-is-an-open-source-software-telecommunications)
- [FreeSWITCH mod_event_socket denial of service via Content-Length](https://junglewise.ai/threats/cve-2026-116787-freeswitch-is-a-software-defined-telecom-stack-enabling-the)
- [FreeSWITCH command injection via SIP REFER URI parameters](https://junglewise.ai/threats/cve-2026-116786-freeswitch-is-a-software-defined-telecom-stack-enabling-the)