CVE-2020-28242: Asterisk Certified Asterisk

Medium severity, CVSS 6.5. EPSS: 1.5% chance of exploitation in the next 30 days.

An issue was discovered in Asterisk Open Source 13.x before 13.37.1, 16.x before 16.14.1, 17.x before 17.8.1, and 18.x before 18.0.1 and Certified Asterisk before 16.8-cert5. If Asterisk is challenged on an outbound INVITE and the nonce is changed in each response, Asterisk will continually send INVITEs in a loop. This causes Asterisk to consume more and more memory since the transaction will never terminate (even if the call is hung up), ultimately leading to a restart or shutdown of Asterisk. Outbound authentication must be configured on the endpoint for this to occur.

Affected products

• Asterisk Certified Asterisk: up to and including 16.8.0
• Debian Debian Linux: version 9.0 only
• Fedoraproject Fedora: version 33 only
• Sangoma Asterisk: from 13.0, before 13.37.1 (fixed in 13.37.1); from 16.0, before 16.14.1 (fixed in 16.14.1); from 17.0, before 17.8.1 (fixed in 17.8.1); from 18.0, before 18.0.1 (fixed in 18.0.1)

Published 2020-11-06. Last modified 2026-06-17.