CVE-2026-84975: high-severity vulnerability in pjsip pjproject
PJSIP: TLS server identity (hostname) verification bypass via embedded NUL in certificate SubjectAltName (OpenSSL and GnuTLS backends)
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.4epss 0.2%
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.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Affected products
pjsip · pjprojectRelated CVEs — pjsip pjproject
In the same product, most dangerous first.
CVE-2021-37706HIGHPotential integer underflow upon receiving STUN message in PJSIPEPSS 4.9%CVE-2022-21723CRITICALOut-of-bounds read in multipart parsing in PJSIPEPSS 4.4%CVE-2022-23608HIGHUse after free in PJSIPEPSS 4.0%CVE-2021-43845HIGHPrevent out-of-bounds read in PJSIPEPSS 3.9%CVE-2022-24764HIGHStack buffer overflow in pjprojectEPSS 2.4%CVE-2022-21722CRITICALPotential out-of-bound read during RTP/RTCP parsing in PJSIPEPSS 2.3%