CVE-2011-2536: Digium Asterisk

Medium severity, CVSS 5.0. EPSS: 1.9% chance of exploitation in the next 30 days.

chan_sip.c in the SIP channel driver in Asterisk Open Source 1.4.x before 1.4.41.2, 1.6.2.x before 1.6.2.18.2, and 1.8.x before 1.8.4.4, and Asterisk Business Edition C.3.x before C.3.7.3, disregards the alwaysauthreject option and generates different responses for invalid SIP requests depending on whether the user account exists, which allows remote attackers to enumerate account names via a series of requests.

Affected products

• Digium Asterisk: version 1.8.0 only; version 1.8.1 only; version 1.8.1.1 only; version 1.8.1.2 only; version 1.8.2 only; version 1.8.2.1 only; …

Published 2011-07-06. Last modified 2026-06-16.