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

• https://nvd.nist.gov/vuln/detail/CVE-2021-26906
• https://downloads.asterisk.org/pub/security/
• https://downloads.asterisk.org/pub/security/AST-2021-005.html
• https://issues.asterisk.org/jira/browse/ASTERISK-29196
• http://packetstormsecurity.com/files/161477/Asterisk-Project-Security-Advisory-AST-2021-005.html
• http://seclists.org/fulldisclosure/2021/Feb/61