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FKIE_CVE-2021-26906

Vulnerability from fkie_nvd - Published: 2021-02-18 20:15 - Updated: 2026-06-17 03:43
Severity
5.9 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
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.
References
cve@mitre.orghttp://packetstormsecurity.com/files/161477/Asterisk-Project-Security-Advisory-AST-2021-005.htmlThird Party Advisory
cve@mitre.orghttp://seclists.org/fulldisclosure/2021/Feb/61Mailing List, Patch, Third Party Advisory
cve@mitre.orghttps://downloads.asterisk.org/pub/security/Vendor Advisory
cve@mitre.orghttps://downloads.asterisk.org/pub/security/AST-2021-005.htmlVendor Advisory
cve@mitre.orghttps://issues.asterisk.org/jira/browse/ASTERISK-29196Issue Tracking, Patch, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108http://packetstormsecurity.com/files/161477/Asterisk-Project-Security-Advisory-AST-2021-005.htmlThird Party Advisory
af854a3a-2127-422b-91ae-364da2661108http://seclists.org/fulldisclosure/2021/Feb/61Mailing List, Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://downloads.asterisk.org/pub/security/Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://downloads.asterisk.org/pub/security/AST-2021-005.htmlVendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://issues.asterisk.org/jira/browse/ASTERISK-29196Issue Tracking, Patch, Vendor Advisory
Impacted products
Vendor Product Version
digium asterisk *
digium asterisk *
digium asterisk *
digium asterisk *
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
digium certified_asterisk 16.8
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
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      ],
      "source": "cve@mitre.org"
    }
  ],
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          "operator": "OR"
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "Se detect\u00f3 un problema en el archivo res_pjsip_session.c en Digium Asterisk versiones hasta 13.38.1;\u0026#xa0;14.x, 15.x y 16.xa 16.16.0;\u0026#xa0;17.xa 17.9.1;\u0026#xa0;y 18.xa 18.2.0, y Certified Asterisk versiones hasta 16.8-cert5.\u0026#xa0;Una vulnerabilidad de negociaci\u00f3n SDP en PJSIP permite a un servidor remoto bloquear potencialmente Asterisk mediante el env\u00edo de respuestas SIP espec\u00edficas que causan un fallo en la negociaci\u00f3n SDP"
    }
  ],
  "id": "CVE-2021-26906",
  "lastModified": "2026-06-17T03:43:58.727",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 4.3,
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:N/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 8.6,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
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          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
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        "impactScore": 3.6,
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  "published": "2021-02-18T20:15:12.743",
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}



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Taxonomy of the tags.





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.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

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.