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CVE-2015-5400

26
FAUCET Score

CVE-2015-5400 describes a vulnerability in Squid versions prior to 3.5.6, where improper handling of CONNECT method peer responses allows remote attackers to bypass access restrictions and gain unauthorized access to a backend proxy. This medium-complexity vulnerability, with a CVSS score of 6.8, could lead to partial compromise of confidentiality, integrity, and availability. Despite its potential impact, there is no evidence of active exploitation, publicly available exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
22CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:22:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
<= 3.5.2CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

6.8MEDIUM

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

Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Exploitability Score
8.6
Impact Score
6.4
CvssVersion
2.0

Exploit Intelligence

EPSS Score
20.84%
Probability of exploitation in next 30 days
EPSS Percentile
97.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.2084 is in the 98th percentile among its peer group of 19,958 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 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

Vendor Patches (3)

redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: squid
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: squid
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: squid

Vendor Advisories (1)

redhatCVE-2015-5400Low

squid: information disclosure due to incorrect handling of peer responses in tunnel.cc (SQUID-2015:2)

Jul 6, 2015

References

lists.fedoraproject.org / pipermail/package-announce/2016-May/183598.html
lists.opensuse.org / opensuse-security-announce/2016-08/msg00010.html
lists.opensuse.org / opensuse-security-announce/2016-08/msg00040.html
lists.opensuse.org / opensuse-updates/2016-08/msg00069.html
debian.org / security/2015/dsa-3327
openwall.com / lists/oss-security/2015/07/06/8
openwall.com / lists/oss-security/2015/07/09/12
openwall.com / lists/oss-security/2015/07/10/2
openwall.com / lists/oss-security/2015/07/17/14
Exploit
securityfocus.com / bid/75553
securitytracker.com / id/1032873
squid-cache.org / Advisories/SQUID-2015_2.txt
Vendor Advisory
squid-cache.org / Versions/v3/3.1/changesets/squid-3.1-10494.patch
ExploitVendor Advisory
squid-cache.org / Versions/v3/3.4/changesets/squid-3.4-13225.patch
ExploitVendor Advisory
squid-cache.org / Versions/v3/3.5/changesets/squid-3.5-13856.patch
ExploitVendor Advisory