CVE-2026-84975 (GCVE-0-2026-84975)

Vulnerability from cvelistv5 – Published: 2026-09-18 17:08 – Updated: 2026-09-18 17:08
VLAI
Title
PJSIP: TLS server identity (hostname) verification bypass via embedded NUL in certificate SubjectAltName (OpenSSL and GnuTLS backends)
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 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.
Severity
7.4 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-295 - Improper Certificate Validation
  • CWE-297 - Improper Validation of Certificate with Host Mismatch
Assigner
References
Impacted products
Vendor Product Version CPE status
pjsip pjproject Affected: <= 2.17
guessed Create a notification for this product.
Show details on NVD website
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        }
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        {
          "descriptions": [
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              "type": "CWE"
            }
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:08:33.140Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
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          "url": "https://github.com/pjsip/pjproject/commit/43d3bd77bb6833eab4c493503b8d564a754ddfdd"
        }
      ],
      "source": {
        "advisory": "GHSA-382p-87mh-r3q8",
        "discovery": "UNKNOWN"
      },
      "title": "PJSIP: TLS server identity (hostname) verification bypass via embedded NUL in certificate SubjectAltName (OpenSSL and GnuTLS backends)"
    }
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  "cveMetadata": {
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    "datePublished": "2026-09-18T17:08:33.140Z",
    "dateReserved": "2026-09-02T18:12:13.533Z",
    "dateUpdated": "2026-09-18T17:08:33.140Z",
    "state": "PUBLISHED"
  },
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  "vulnerability-lookup:meta": {
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                    "version": "\u003c= 2.17"
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        "cveTags": [],
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            "value": "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."
          }
        ],
        "id": "CVE-2026-84975",
        "lastModified": "2026-09-18T18:17:17.127",
        "metrics": {
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        "vulnStatus": "Received",
        "weaknesses": [
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                "value": "CWE-295"
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    "redhat_vex": {
      "current_release_date": "2026-09-23T11:59:16+00:00",
      "cve": "CVE-2026-84975",
      "id": "CVE-2026-84975",
      "initial_release_date": "2026-09-18T17:08:33.140000+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "pjproject: PJSIP: Server impersonation via TLS certificate hostname bypass",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-84975.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.