---
id: CVE-2026-84975
title: PJSIP is a free and open source multimedia communication library written in C
summary: >-
  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 stri…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-295
  - CWE-297
vendor: pjsip
product: pjproject
affected:
  - pjproject <= 2.17
published: '2026-09-18'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:18:55.637'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84975'
references:
  - url: >-
      https://github.com/pjsip/pjproject/commit/43d3bd77bb6833eab4c493503b8d564a754ddfdd
    label: security-advisories@github.com
  - url: 'https://github.com/pjsip/pjproject/security/advisories/GHSA-382p-87mh-r3q8'
    label: security-advisories@github.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84975.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-84975'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-84975'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-24T21:00:46.376266Z'
epss: 0.00232
epssPercentile: 0.12491
ingestedAt: '2026-09-18T17:46:41.552Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84975.json)