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Fencer Intel
high 8.6

CVE-2016-4553 in the critical feed json

client_side.cc in Squid before 3.5.18 and 4.x before 4.0.10 does not properly ignore the Host header when absolute-URI is provided, which a…

published 2016-05-10 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-5540

cvss
8.6
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
80.0%
EPSS 80.0% chance of exploitation in 30 days, percentile 99.6%
public exploits
0
none known

Summary

client_side.cc in Squid before 3.5.18 and 4.x before 4.0.10 does not properly ignore the Host header when absolute-URI is provided, which allows remote attackers to conduct cache-poisoning attacks via an HTTP request.

Patch / fix

  • squid3 Ubuntu 14.04 LTS 3.3.8-1ubuntu6.8
  • squid3 Ubuntu 16.04 LTS 3.5.12-1ubuntu7.2

ubuntu advisories UBUNTU-CVE-2016-4553

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • squid RHEL 7 7:3.3.8-26.el7_2.3
  • squid-sysvinit RHEL 7 7:3.3.8-26.el7_2.3
  • squid34 RHEL 6 7:3.4.14-9.el6_8.3

red hat advisories RHSA-2016:1139RHSA-2016:1140

  • squid3 SLES for SAP 11 SP4, SLES 11 SP4 3.1.23-8.16.30.1
  • squid SLES for SAP 12 SP1, SLES 12 SP1 3.3.14-20.2

suse advisories SUSE-SU-2016:2089-1SUSE-SU-2016:2008-1

  • squid openSUSE Tumbleweed 4.16-1.5

opensuse advisories openSUSE-SU-2024:11403-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-4553 updated cvss 4.3

squid: Cache poisoning issue in HTTP Request handling

  • Red Hat Enterprise Linux Server (v. 6) squid34 3.4.14-9.el6_8.3
    fixed: vendor fix RHSA-2016:1140
  • Red Hat Enterprise Linux Server (v. 7) squid 3.3.8-26.el7_2.3 Red Hat Enterprise Linux Server Optional (v. 7) squid-sysvinit 3.3.8-26.el7_2.3
    fixed: vendor fix RHSA-2016:1139
  • Red Hat Enterprise Linux Workstation (v. 6) squid34 3.4.14-9.el6_8.3
    fixed: vendor fix RHSA-2016:1140
  • Red Hat Enterprise Linux Workstation (v. 7) squid 3.3.8-26.el7_2.3 Red Hat Enterprise Linux Workstation Optional (v. 7) squid-sysvinit 3.3.8-26.el7_2.3
    fixed: vendor fix RHSA-2016:1139
  • Red Hat Enterprise Linux 5 squid Red Hat Enterprise Linux 6 squid
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

79.97% chance of exploitation in the next 30 days, higher than 99.6% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 8.6 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-345 Insufficient Verification of Data Authenticity

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.