Vulnerability · Published Sep 18, 2026 · Assigned by GitHub_M
CVE-2026-84975PJSIP: TLS server identity (hostname) verification bypass via embedded NUL in certificate SubjectAltName (OpenSSL and GnuTLS backends)
High 7.4
In plain English
A high-severity improper certificate validation in pjproject from pjsip. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities).
Official description
PJSIP is a free and open source multimedia communication library written in C. In 2.17 and earlier, the OpenSSL and GnuTLS backends in pjlib/src/pj/ssl_sock_ossl.c and pjlib/src/pj/ssl_sock_gtls.c copy DNS SubjectAltName values with string functions that recalculate their length and truncate an embedded NUL byte. With server verification enabled through --tls-verify-server for the PJSIP TLS/SIPS transport, a certificate containing a DNS SubjectAltName formed from the target hostname prefix followed by an embedded NUL and an attacker-controlled suffix can therefore be accepted for the prefix hostname. An attacker who possesses such a certificate from a trusted issuer and can intercept the connection can impersonate the target server, complete the SIP session, and receive REGISTER credentials. The mbedTLS backend is not affected because it preserves the explicit string length. No fixed version is available as of this review.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:14 | asterisk | no fix listed | DEBIAN-CVE-2026-84975 |
| Ubuntu:22.04:LTS | asterisk | no fix listed | UBUNTU-CVE-2026-84975 |
| Ubuntu:24.04:LTS | asterisk | no fix listed | UBUNTU-CVE-2026-84975 |
| Ubuntu:26.04:LTS | asterisk | no fix listed | UBUNTU-CVE-2026-84975 |
| Ubuntu:26.10 | asterisk | no fix listed | UBUNTU-CVE-2026-84975 |
Affected products (as reported)
Weakness: CWE-295, CWE-297 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N