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CVE-2009-2855

34
FAUCET Score

CVE-2009-2855 describes a denial-of-service vulnerability in Squid 2.7, specifically within the strListGetItem function in src/HttpHeaderTools.c. This flaw allows remote attackers to trigger an infinite loop by submitting a specially crafted authentication header containing certain comma delimiters. With a CVSS score of 5.0 (AV:N/AC:L/Au:N/C:N/I:N/A:P), it represents a medium-severity issue with low attack complexity, requiring no authentication, and primarily impacting availability. There is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
2.7CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:2.7:*:*:*:*:*:*:*
2.7CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:2.7:stable3:*:*:*:*:*:*
2.7CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:2.7:stable4:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

5.0MEDIUM

AV:N/AC:L/Au:N/C:N/I:N/A:P

Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
2.9
CvssVersion
2.0

Exploit Intelligence

EPSS Score
36.73%
Probability of exploitation in next 30 days
EPSS Percentile
98.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.3673 is in the 99th percentile among its peer group of 23,725 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: squid-7:2.6.STABLE21-6.el5
View patch

Vendor Advisories (1)

redhatCVE-2009-2855Low

squid: DoS (100% CPU use) while processing certain external ACL helper HTTP headers

Jun 28, 2009

References

bugs.debian.org / cgi-bin/bugreport.cgi
bugs.debian.org / cgi-bin/bugreport.cgi
bugzilla.redhat.com / show_bug.cgi
exchange.xforce.ibmcloud.com / vulnerabilities/52610
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10592
openwall.com / lists/oss-security/2009/07/20/10
openwall.com / lists/oss-security/2009/08/03/3
openwall.com / lists/oss-security/2009/08/04/6
securityfocus.com / bid/36091
securitytracker.com / id
squid-cache.org / bugs/show_bug.cgi
squid-cache.org / bugs/show_bug.cgi
Vendor Advisory