Description
Squid 2.7 to 2.7.STABLE5, 3.0 to 3.0.STABLE12, and 3.1 to 3.1.0.4 allows remote attackers to cause a denial of service via an HTTP request with an invalid version number, which triggers a reachable assertion in (1) HttpMsg.c and (2) HttpStatusLine.c.
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 | 2.7.STABLE3-4.1 | — |
| Debian 13 | squid | 2.7.STABLE3-4.1 | — |
| Debian 12 | squid | 2.7.STABLE3-4.1 | — |
| Debian 4.0 | squid3 | 3.0.PRE5-5+etch1 | DSA-1732-1 |
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.
Exploit-DB 1
- Squid < 3.1 5 - HTTP Version Number Parsing Denial of Service EDB-8021 · dos · Feb 9, 2009 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 1
- DSA-1732-1 squid3 - denial of service Debian Security (DSA / DLA) · Mar 9, 2026
References
- 33604 vdb-entry
- 33731 third-party-advisory
- GLSA-200903-38 vendor-advisory
- 20090204 Squid Proxy Cache Denial of Service in request handling mailing-list
- SUSE-SR:2009:005 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=484246
- http://www.squid-cache.org/Versions/v2/2.7/changesets/12432.patch
- 1021684 vdb-entry
- http://www.squid-cache.org/Advisories/SQUID-2009_1.txt
- MDVSA-2009:034 vendor-advisory
- 8021 exploit
- 34467 third-party-advisory