{"cve":"CVE-2011-2536","nvd":{"published":"2011-07-06T19:55:03.543","modified":"2026-06-16T23:31:33.883","status":"Modified","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.","cvss_v4":null,"cvss_v3":null,"cwes":["CWE-200"],"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"],"products":["digium:asterisk"],"source":"nvd","synced_at":"2026-10-19T19:58:50.521460154+00:00"},"epss":{"cve":"CVE-2011-2536","score":0.01945,"percentile":0.80177,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}