What is CVE-2016-4553?

CVE-2016-4553 is a high-severity vulnerability in Oracle Linux, classified under Insufficient Verification of Data Authenticity. CVSS score: 8.6/10. Published 2016-05-10.

How severe is CVE-2016-4553?

High severity. CVSS v3 base score is 8.6 out of 10.

Is CVE-2016-4553 known to be exploited?

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

Vulnerability in Oracle Linux

CVE-2016-4553

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.

Published 2016-05-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.6 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.800 (99.6th percentile), scored 2026-10-15.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.788 · newest: 0.800 · change: +0.012

Affected products

Oracle Linux — versions 7
Squid-Cache Squid — versions 4.0.1, 4.0.2, 4.0.3
Canonical Ubuntu Linux — versions 12.04, 14.04, 15.10

Weakness classification (CWE)

CWE-345 — Insufficient Verification of Data Authenticity

Public proof-of-concept exploits

ARPSyndicate/cve-scores

References

security.gentoo.org/glsa/201607-01 (vendor-advisory)
www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html (Third Party Advisory)
bugs.squid-cache.org/show_bug.cgi (Vendor Advisory)
lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html (vendor-advisory)
www.squid-cache.org/Advisories/SQUID-2016_7.txt (Vendor Advisory)
www.ubuntu.com/usn/USN-2995-1 (vendor-advisory, Third Party Advisory)
www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14039.patch
access.redhat.com/errata/RHSA-2016:1140 (vendor-advisory)
lists.opensuse.org/opensuse-updates/2016-08/msg00069.html (vendor-advisory)
access.redhat.com/errata/RHSA-2016:1139 (vendor-advisory)

Frequently asked questions

What is CVE-2016-4553?: CVE-2016-4553 is a high-severity vulnerability in Oracle Linux, classified under Insufficient Verification of Data Authenticity. CVSS score: 8.6/10. Published 2016-05-10.
How severe is CVE-2016-4553?: High severity. CVSS v3 base score is 8.6 out of 10.
Is CVE-2016-4553 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.