No exploitation reportedFix available

CVE-2016-4554

No exploitation reported by the sources we read.

Published2016-05-10
WeaknessCWE-345

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2016-05-1019:59CVE publishedNVD
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2016-4554?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2016-4554?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Canonical ubuntu linux

Branch	Affected	Fixed in	Source
12.4	= 12.04	no fix published	NVD
14.4	= 14.04	no fix published	NVD
15.10	= 15.10	no fix published	NVD
16.4	= 16.04	no fix published	NVD

Oracle linux

Branch	Affected	Fixed in	Source
6.x	= 6	no fix published	NVD
7.x	= 7	no fix published	NVD

Squid-cache squid

Branch	Affected	Fixed in	Source
3.5	≤ 3.5.17	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.08.6read 2026-10-23
NVDCVSS 2.05read 2026-10-23
NVDweakness (CWE)CWE-345read 2026-10-23
FIRST EPSSEPSS score38.9 %read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Published: 2016-05-10
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2016-4554?

Is CVE-2016-4554 actively exploited?

Active exploitation of CVE-2016-4554 has not been confirmed. Its EPSS score was 38.9% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2016-4554?

CVE-2016-4554 has a CVSS v3 base score of 8.6 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N.

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