What is CVE-2016-2571?

CVE-2016-2571 is a high-severity vulnerability in Squid-Cache Squid, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2016-02-27.

How severe is CVE-2016-2571?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2016-2571 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Improper input validation in Squid-Cache Squid

CVE-2016-2571

http.cc in Squid 3.x before 3.5.15 and 4.x before 4.0.7 proceeds with the storage of certain data after a response-parsing failure, which allows remote HTTP servers to cause a denial of service (assertion failure and daemon exit) via a malformed response.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2016-02-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.093 (95.2th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 95th percentile — 95.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.093 · newest: 0.093 · change: 0.000

Affected products

Squid-Cache Squid — versions 3.0, 3.0.stable1, 3.0.stable2

Weakness classification (CWE)

CWE-20 — Improper Input Validation

Public proof-of-concept exploits

ARPSyndicate/cvemon

References

usn.ubuntu.com/3557-1/ (vendor-advisory)
security.gentoo.org/glsa/201607-01 (vendor-advisory)
www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-13990.patch
www.squid-cache.org/Advisories/SQUID-2016_2.txt (Vendor Advisory)
lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html (vendor-advisory)
www.debian.org/security/2016/dsa-3522 (vendor-advisory)
rhn.redhat.com/errata/RHSA-2016-2600.html (vendor-advisory)
www.squid-cache.org/Versions/v4/changesets/squid-4-14548.patch
lists.opensuse.org/opensuse-updates/2016-08/msg00069.html (vendor-advisory)
www.openwall.com/lists/oss-security/2016/02/26/2 (mailing-list)

Frequently asked questions

What is CVE-2016-2571?: CVE-2016-2571 is a high-severity vulnerability in Squid-Cache Squid, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2016-02-27.
How severe is CVE-2016-2571?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2016-2571 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.