CVE-2011-2536

Severity: medium (CVSS 5.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2011-07-06 · updated 2026-06-16
Weakness: CWE-200

Description

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: 1.8.0, 1.8.0-beta1, 1.8.0-beta2, 1.8.0-beta3, 1.8.0-beta4, 1.8.0-beta5 (+192)

References

http://downloads.asterisk.org/pub/security/AST-2011-011-1.8.diff
http://downloads.asterisk.org/pub/security/AST-2011-011.html
http://www.securitytracker.com/id?1025734
http://downloads.asterisk.org/pub/security/AST-2011-011-1.8.diff
http://downloads.asterisk.org/pub/security/AST-2011-011.html
http://www.securitytracker.com/id?1025734

Get alerted when CVE-2011-2536 or the next vulnerability affects your stack