CVE-2009-3727: Digium Asterisk

Medium severity, CVSS 5.0. EPSS: 4.2% chance of exploitation in the next 30 days.

Asterisk Open Source 1.2.x before 1.2.35, 1.4.x before 1.4.26.3, 1.6.0.x before 1.6.0.17, and 1.6.1.x before 1.6.1.9; Business Edition A.x.x, B.x.x before B.2.5.12, C.2.x.x before C.2.4.5, and C.3.x.x before C.3.2.2; AsteriskNOW 1.5; and s800i 1.3.x before 1.3.0.5 generate different error messages depending on whether a SIP username is valid, which allows remote attackers to enumerate valid usernames via multiple crafted REGISTER messages with inconsistent usernames in the URI in the To header and the Digest in the Authorization header.

Affected products

• Digium Asterisk: version 1.2.0 only; version 1.2.1 only; version 1.2.2 only; version 1.2.3 only; version 1.2.10 only; version 1.2.11 only; …
• Digium Asterisknow: version 1.5 only
• Digium s800i: version 1.3.0 only; version 1.3.0.2 only; version 1.3.0.3 only; version 1.3.0.4 only

Published 2009-11-10. Last modified 2026-06-16.