CVE-2009-2855 Denial of service in n/a
Remote attackers can cause a denial of service in Squid proxy servers by sending crafted authentication headers that trigger an infinite loop.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2009-2855?
CVE-2009-2855 is a medium-severity denial of service vulnerability in Squid-Cache Squid, published on 18 Aug 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The strListGetItem function in src/HttpHeaderTools.c in Squid 2.7 allows remote attackers to cause a denial of service via a crafted auth header with certain comma delimiters that trigger an infinite loop of calls to the strcspn function.
Weakness: CWE-20
Which versions are affected by CVE-2009-2855?
It affects 1 product.
Products include Squid-Cache Squid.
How do I fix CVE-2009-2855?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2009-2855 being exploited?
There is no known exploitation of CVE-2009-2855 in the wild and no public exploit code.
Other vulnerabilities in Squid-Cache Squid
- CVE-2025-62168 Squid vulnerable to information disclosure via authentication credential leakage in error handling
- CVE-2025-54574 Squid's URN Handling can lead to Buffer Overflow
- CVE-2026-33526 Squid vulnerable to Denial of Service in ICP Request handling
- CVE-2026-32748 Squid has Denial of Service in ICP Response handling
- CVE-2023-50269 SQUID-2023:10 Denial of Service in HTTP Request parsing
Sources
Also known as DEBIAN-CVE-2009-2855, GHSA-7hrp-6jq3-pm4q.