How severe is CVE-2009-2855?

CVE-2009-2855 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2009-2855 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 37% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-2855?

CVE-2009-2855 primarily affects Squid-cache Squid. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-2855?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2009-2855 published?

CVE-2009-2855 was published on 2009-08-18 and last updated on 2026-06-16.

CVE-2009-2855

CVE-2009-2855 is a medium-severity vulnerability in Squid-cache Squid with a CVSS 2.0 base score of 5.0. Its EPSS exploit-prediction score of 37% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Severity: Medium (CVSS 2.0 base score 5.0)
EPSS exploit prediction: 37% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Squid-cache Squid
Published: 2009-08-18
Last modified: 2026-06-16

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.

Frequently asked questions

What is CVE-2009-2855?: 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.
How severe is CVE-2009-2855?: CVE-2009-2855 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-2009-2855 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 37% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-2855?: CVE-2009-2855 primarily affects Squid-cache Squid. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-2855?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2009-2855 published?: CVE-2009-2855 was published on 2009-08-18 and last updated on 2026-06-16.

References

Affected products (3)

cpe:2.3:a:squid-cache:squid:2.7:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable3:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable4:*:*:*:*:*:*

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