How severe is CVE-2015-5400?

CVE-2015-5400 has a CVSS 2.0 base score of 6.8, rated medium severity.

Is CVE-2015-5400 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-5400?

CVE-2015-5400 primarily affects Squid-cache Squid. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-5400?

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

When was CVE-2015-5400 published?

CVE-2015-5400 was published on 2015-09-28 and last updated on 2026-06-17.

CVE-2015-5400

CVE-2015-5400 is a medium-severity vulnerability in Squid-cache Squid with a CVSS 2.0 base score of 6.8. Its EPSS exploit-prediction score of 17% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-264.

Key facts

Severity: Medium (CVSS 2.0 base score 6.8)
EPSS exploit prediction: 17% (97th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-264
Affected product: Squid-cache Squid
Published: 2015-09-28
Last modified: 2026-06-17

Description

Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.

Frequently asked questions

What is CVE-2015-5400?: Squid before 3.5.6 does not properly handle CONNECT method peer responses when configured with cache_peer, which allows remote attackers to bypass intended restrictions and gain access to a backend proxy via a CONNECT request.
How severe is CVE-2015-5400?: CVE-2015-5400 has a CVSS 2.0 base score of 6.8, rated medium severity.
Is CVE-2015-5400 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-5400?: CVE-2015-5400 primarily affects Squid-cache Squid. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2015-5400?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2015-5400 published?: CVE-2015-5400 was published on 2015-09-28 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:o:fedoraproject:fedora:22:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*

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