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CVE-2016-2571

25
FAUCET Score

CVE-2016-2571 describes a denial-of-service vulnerability in Squid versions 3.x before 3.5.15 and 4.x before 4.0.7. Remote HTTP servers can trigger an assertion failure and daemon exit by sending a malformed response, causing the Squid proxy to crash. This vulnerability has a CVSS v3 score of 7.5 (High), indicating it can be exploited remotely with low attack complexity and no user interaction, leading to high availability impact. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
3.0CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:3.0:*:*:*:*:*:*:*
3.0CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:3.0:-:pre1:*:*:*:*:*
3.0CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:3.0:-:pre2:*:*:*:*:*
3.0CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:3.0:-:pre3:*:*:*:*:*
3.0CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:3.0:-:pre4:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
9.29%
Probability of exploitation in next 30 days
EPSS Percentile
94.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0929 is in the 92nd percentile among its peer group of 51,485 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: squid-7:3.5.20-2.el7
View patch
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 6Fixed in: squid34

Vendor Advisories (1)

redhatCVE-2016-2571Moderate

squid: wrong error handling for malformed HTTP responses

Feb 24, 2016

References

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
rhn.redhat.com / errata/RHSA-2016-2600.html
security.gentoo.org / glsa/201607-01
usn.ubuntu.com / 3557-1
debian.org / security/2016/dsa-3522
openwall.com / lists/oss-security/2016/02/26/2
securitytracker.com / id/1035101
squid-cache.org / Advisories/SQUID-2016_2.txt
Vendor Advisory
squid-cache.org / Versions/v3/3.5/changesets/squid-3.5-13990.patch
squid-cache.org / Versions/v4/changesets/squid-4-14548.patch
ubuntu.com / usn/USN-2921-1