{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "13.0.0"
              },
              {
                "fixed": "13.38.2"
              },
              {
                "introduced": "16.0.0"
              },
              {
                "fixed": "16.16.1"
              },
              {
                "introduced": "17.0.0"
              },
              {
                "fixed": "17.9.2"
              },
              {
                "introduced": "18.0"
              },
              {
                "fixed": "18.2.1"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-NA"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert1\\-rc1"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert1\\-rc2"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert1\\-rc3"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert1\\-rc4"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert2"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert3"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert4"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert4\\-rc1"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert4\\-rc2"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert4\\-rc3"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert4\\-rc4"
              },
              {
                "introduced": "0"
              },
              {
                "last_affected": "16.8-cert5"
              }
            ]
          },
          "events": [
            {
              "introduced": "85335355efb2d7914a1fe20ed31afcef15fd210c"
            },
            {
              "fixed": "fbaea22493a6061d4bdc87bddc0cb5971e5f71d9"
            },
            {
              "introduced": "a65908f83e2f17a3aca7eb39c8e06045aca02674"
            },
            {
              "fixed": "3cd8afbdf2c6dffe80c631a5336e21bb1827a5cd"
            },
            {
              "introduced": "5ffe12b6ef30cd503f85d75745fd8d9c2cfafe47"
            },
            {
              "fixed": "fdaf2d0689b7a8928a45019c9af14c53bcdfa6e3"
            },
            {
              "introduced": "2c1bba3cbec008c8ce35c78a2c79f9f207ea58bc"
            },
            {
              "fixed": "332130c4389803a3c7e63cabf00daf5ac66a3068"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "d436f568583184a13aa46349af5a3f0907087b44"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "476bbcf3a3a8439c469ab31677cc87bbfd2fb214"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "7b8157645f8c5f8599f160cd3374d2763564b55f"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "d1bb76a27d2b8b4e4d32e77e8090997400f1d46d"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "3d317239d5e94f07d387b31c46a6733cbc43e5ef"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "bbaf9042cff308827c91e8235179b7ba27b48a33"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "4d7a90d4e2c408af10dce738d6fc5ca491fcc83e"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "21635f1e4075f13c8aabc6d9abdf183df416156b"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "aabb04054a92d531c2ed82832e6d155a297253d1"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "017416381fdcb5d222de2c2f39b17672506b061b"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "cb9f1759fb996c99d5391135dd97db6f1e2d3387"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "f777a0d87982e4f780099257e8157ec5341fb488"
            },
            {
              "introduced": "0"
            },
            {
              "last_affected": "10b274d1aba4fc2cf2a8cabcb66eb2a049e2250f"
            }
          ],
          "repo": "https://github.com/asterisk/asterisk",
          "type": "GIT"
        }
      ]
    }
  ],
  "details": "An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.",
  "id": "CVE-2021-26906",
  "modified": "2026-04-01T23:08:21.558775292Z",
  "published": "2021-02-18T20:15:12.743Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "http://packetstormsecurity.com/files/161477/Asterisk-Project-Security-Advisory-AST-2021-005.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://downloads.asterisk.org/pub/security/"
    },
    {
      "type": "ADVISORY",
      "url": "https://downloads.asterisk.org/pub/security/AST-2021-005.html"
    },
    {
      "type": "FIX",
      "url": "http://seclists.org/fulldisclosure/2021/Feb/61"
    },
    {
      "type": "FIX",
      "url": "https://issues.asterisk.org/jira/browse/ASTERISK-29196"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}