What is CVE-2016-4554?

CVE-2016-4554 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-2016-4554?

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

Is CVE-2016-4554 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-2016-4554

mime_header.cc in Squid before 3.5.18 allows remote attackers to bypass intended same-origin restrictions and possibly conduct cache-poisoning attacks via a crafted HTTP Host header, aka a "header smuggling" issue.

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: 0.389 (98.5th percentile), scored 2026-09-27.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.389 · newest: 0.389 · change: 0.000

Affected products

Oracle Linux — versions 6, 7
Squid-Cache Squid
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)
www.squid-cache.org/Versions/v3/3.3/changesets/SQUID-2016_8.patch (Patch)
www.squid-cache.org/Versions/v3/3.4/changesets/SQUID-2016_8.patch (Patch)
lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html (vendor-advisory)
www.squid-cache.org/Versions/v3/3.1/changesets/SQUID-2016_8.patch (Patch)
www.ubuntu.com/usn/USN-2995-1 (vendor-advisory, Third Party Advisory)
www.securitytracker.com/id/1035769 (Third Party Advisory, vdb-entry)
www.squid-cache.org/Versions/v3/3.2/changesets/SQUID-2016_8.patch (Patch)
access.redhat.com/errata/RHSA-2016:1140 (vendor-advisory)

Frequently asked questions

What is CVE-2016-4554?: CVE-2016-4554 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-2016-4554?: High severity. CVSS v3 base score is 8.6 out of 10.
Is CVE-2016-4554 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.