Vulnerability Monitor

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CVE-2021-26906

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.

Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 5.9, indicating it can be exploited remotely over the network but requires specific conditions to be met without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 2 products from digium, from digium organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2021-02-18T20:15:12.743

Last Modified

2024-11-21T05:57:00.817

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 5.9 (MEDIUM)

CVSSv2 Vector

AV:N/AC:M/Au:N/C:N/I:N/A:P

Access Vector: NETWORK
Access Complexity: MEDIUM
Authentication: NONE
Confidentiality Impact: NONE
Integrity Impact: NONE
Availability Impact: PARTIAL

Exploitability Score

8.6

Impact Score

2.9

Weaknesses

Type: Primary
CWE-404

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	digium	asterisk	< 13.38.2	Yes
Application	digium	asterisk	< 16.16.1	Yes
Application	digium	asterisk	< 17.9.2	Yes
Application	digium	asterisk	< 18.2.1	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes
Application	digium	certified_asterisk	16.8	Yes

References

http://packetstormsecurity.com/files/161477/Asterisk-Project-Security-Advisory-AST-2021-005.html Third Party Advisory ([email protected])
http://seclists.org/fulldisclosure/2021/Feb/61 Mailing List, Patch, Third Party Advisory ([email protected])
https://downloads.asterisk.org/pub/security/ Vendor Advisory ([email protected])
https://downloads.asterisk.org/pub/security/AST-2021-005.html Vendor Advisory ([email protected])
https://issues.asterisk.org/jira/browse/ASTERISK-29196 Issue Tracking, Patch, Vendor Advisory ([email protected])
http://packetstormsecurity.com/files/161477/Asterisk-Project-Security-Advisory-AST-2021-005.html Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
http://seclists.org/fulldisclosure/2021/Feb/61 Mailing List, Patch, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://downloads.asterisk.org/pub/security/ Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://downloads.asterisk.org/pub/security/AST-2021-005.html Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://issues.asterisk.org/jira/browse/ASTERISK-29196 Issue Tracking, Patch, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For digium's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.