What’s Vulnerable › Vulnerabilities

CVE-2020-28242

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-11-06 · updated 2026-06-17
• Weakness: CWE-674

Description

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: through 16.8.0
• Debian Linux: 9.0
• Fedoraproject Fedora: 33
• asterisk: from 13.0 before 13.37.1; from 16.0 before 16.14.1; from 17.0 before 17.8.1; from 18.0 before 18.0.1 — fixed in 13.37.1, 16.14.1, 17.8.1, 18.0.1

How to fix

Upgrade to a fixed version: asterisk 13.37.1, 16.14.1, 17.8.1, 18.0.1. Check the vendor advisory for mitigations.

References

• http://downloads.asterisk.org/pub/security/AST-2020-002.html
• https://lists.debian.org/debian-lts-announce/2022/04/msg00001.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QUS54QTQCYKR36EIULYD544GXDA644HB/
• http://downloads.asterisk.org/pub/security/AST-2020-002.html
• https://lists.debian.org/debian-lts-announce/2022/04/msg00001.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QUS54QTQCYKR36EIULYD544GXDA644HB/

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