Description
Buffer overflow in the ntlm_check_auth (NTLM authentication) function for Squid Web Proxy Cache 2.5.x and 3.x, when compiled with NTLM handlers enabled, allows remote attackers to execute arbitrary code via a long password ("pass" variable).
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | squid | 2.5.5-5 | — |
| Debian 13 | squid | 2.5.5-5 | — |
| Debian 12 | squid | 2.5.5-5 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 3 | squid | 7:2.5.STABLE3-6.3E | RHSA-2004:242 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Metasploit 1 module
-
Squid NTLM Authenticate Overflow
exploit/linux/proxy/squid_ntlm_authenticate
Exploit-DB 2
- Squid - NTLM (Authenticated) Overflow (Metasploit) EDB-16847 · remote · Apr 30, 2010 · verified
- Squid 2.5.x/3.x - NTLM Buffer Overflow (Metasploit) EDB-9951 · remote · Jun 8, 2004 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 1
- RHSA-2004:242 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
References
- oval:org.mitre.oval:def:10722 vdb-entry signature
- RHSA-2004:242 vendor-advisory
- GLSA-200406-13 vendor-advisory
- MDKSA-2004:059 vendor-advisory
- FLSA-2006:152809 vendor-advisory
- http://www.idefense.com/application/poi/display?id=107&type=vulnerabilities
- squid-ntlm-bo(16360) vdb-entry
- 10500 vdb-entry
- 2004-0033 vendor-advisory
- oval:org.mitre.oval:def:980 vdb-entry signature