CVE-2026-116789: FreeSWITCH: DTLS-SRTP peer certificate is not bound to the SDP fingerprint when FreeSWITCH is the DTLS server

Vulnerability summary

CVE-2026-116789 is a high (CVSS 7.4) Improper Certificate Validation vulnerability in signalwire freeswitch. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.4% of scored vulnerabilities.

Timeline

1. 05-11-2026
   PublishedVulnerability first disclosed.
2. 09-11-2026
   Last modifiedVulnerability information updated.

Description

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, dtls_state_setup() compared a peer certificate with the SDP a=fingerprint only when FreeSWITCH was the DTLS client, not when it held the DTLS server role. An unauthenticated peer able to reach the negotiated media port could complete the DTLS-SRTP handshake with an unrelated certificate, obtain the leg's SRTP keys, decrypt and inject media, and displace the legitimate endpoint; on ICE-enabled legs the peer also needs the connectivity-check credentials from SDP, which generally requires signaling visibility or a position on its path. WebRTC and SIP DTLS-SRTP legs are affected whenever the peer selects the active role, while FreeSWITCH client-role handshakes already perform fingerprint validation. Version 1.11.2 introduces the remediation, which requires rtp_dtls_client_cert_verify_mode=fingerprint.

• CWE-295Improper Certificate ValidationThe product does not validate, or incorrectly validates, a certificate.
• CWE-300Channel Accessible by Non-EndpointThe product does not adequately verify the identity of actors at both ends of a communication channel, or does not adequately ensure the integrity of the channel, in a way that allows the channel to be accessed or influenced by an actor that is not an endpoint.