CVE-2016-4553

CRITICALNVD 8.69.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because EPSS predicts 80% probability of exploitation within the next 30 days (top 0.4% of all CVEs). NVD baseline CVSS 8.6 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, ghsa, nvd
Elevated
9.0EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 80%
CISA-KEV: Not listedEPSS PROB: 80%CVSS: 8.6Exploit: Elevated riskExposed: 0

A fix is available — apply it.

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.

CVSS v3
8.6
EG Score
9.0(high)
EG Risk
77(Track)
EG Risk 77/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation80% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
80%
EPSS %ILE
100%
KEV
Not listed

Published

May 10, 2016

Last Modified

June 17, 2026

Advisory Details (5)

Auto-updated Sep 1, 2026
Patch available.
generic
http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14039.patch
generic Patch Available
http://www.squid-cache.org/Advisories/SQUID-2016_7.txt
generic
http://www.securitytracker.com/id/1035768
generic Patch Available

[SECURITY] [DSA 3625-1] squid3 security update

http://www.debian.org/security/2016/dsa-3625
generic

Log in to Bugzilla

http://bugs.squid-cache.org/show_bug.cgi?id=4501

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntusquidclient (3.5.12-1ubuntu7.2) @ xenial2026-05-22ubuntu
redhatsquid34-7:3.4.14-9.el6_8.32016-05-31redhat
redhatsquid-7:3.3.8-26.el7_2.32016-05-31redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Debian:8(1)
PackageVulnerable rangeFixed inDependents
squid33.4.8-6, 3.4.8-6+deb8u1, 3.4.8-6+deb8u2, 3.4.8-6+deb8u2~bpo70+13.4.8-6+deb8u3—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(3)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 1× in last 7d / 11× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-10 09:26 UTCEPSS rescore
  2. 2026-09-04 13:56 UTCEPSS rescore
  3. 2026-09-02 14:07 UTCEPSS rescore
  4. 2026-08-31 04:20 UTCOSV refresh
  5. 2026-08-30 19:12 UTCEPSS rescore
  6. 2026-08-26 14:41 UTCEPSS rescore
  7. 2026-08-21 23:44 UTCEPSS rescore
  8. 2026-08-19 16:59 UTCEPSS rescore
  9. 2026-08-16 02:09 UTCEPSS rescore
  10. 2026-08-15 01:25 UTCEPSS rescore
  11. 2026-08-14 12:16 UTCOSV refresh
  12. 2026-08-12 13:46 UTCEPSS rescore
  13. 2026-08-11 13:36 UTCEPSS rescore
  14. 2026-08-04 10:32 UTCEPSS rescore
  15. 2026-07-30 00:37 UTCOSV refresh
  16. 2026-07-28 15:31 UTCEPSS rescore
  17. 2026-07-26 14:50 UTCEPSS rescore
  18. 2026-07-25 14:13 UTCEPSS rescore
  19. 2026-07-23 01:23 UTCEG score recompute▲ 0.40
  20. 2026-07-22 22:02 UTCEG score recompute
  21. 2026-07-22 14:04 UTCEPSS rescore
  22. 2026-07-21 15:21 UTCEPSS rescore
  23. 2026-07-21 15:21 UTCEPSS rescore
  24. 2026-07-20 17:03 UTCEPSS rescore
  25. 2026-07-16 16:59 UTCEPSS rescore
Show 45 more
  1. 2026-07-16 16:59 UTCEPSS rescore
  2. 2026-07-15 16:54 UTCEPSS rescore
  3. 2026-07-15 16:54 UTCEPSS rescore
  4. 2026-07-13 06:09 UTCEPSS rescore
  5. 2026-07-12 10:08 UTCOSV refresh
  6. 2026-07-11 08:23 UTCEPSS rescore
  7. 2026-07-06 16:24 UTCEPSS rescore
  8. 2026-07-06 16:24 UTCEPSS rescore
  9. 2026-07-01 15:02 UTCEPSS rescore
  10. 2026-06-28 04:53 UTCEPSS rescore
  11. 2026-06-25 13:47 UTCEPSS rescore
  12. 2026-06-25 13:47 UTCEPSS rescore
  13. 2026-06-24 14:02 UTCEPSS rescore
  14. 2026-06-24 14:02 UTCEPSS rescore
  15. 2026-06-23 21:30 UTCEPSS rescore
  16. 2026-06-23 15:30 UTCOSV refresh
  17. 2026-06-21 14:54 UTCEPSS rescore
  18. 2026-06-21 14:54 UTCEPSS rescore
  19. 2026-06-17 17:50 UTCEPSS rescore
  20. 2026-06-17 17:50 UTCEPSS rescore
  21. 2026-06-15 17:45 UTCEPSS rescore
  22. 2026-06-14 23:14 UTCEPSS rescore
  23. 2026-06-12 23:09 UTCEPSS rescore
  24. 2026-06-12 23:09 UTCEPSS rescore
  25. 2026-06-10 22:15 UTCEPSS rescore
  26. 2026-06-10 13:18 UTCEPSS rescore
  27. 2026-06-08 14:14 UTCEPSS rescore
  28. 2026-06-06 19:59 UTCOSV refresh
  29. 2026-06-05 22:44 UTCEPSS rescore
  30. 2026-06-04 13:10 UTCEPSS rescore
  31. 2026-06-04 13:10 UTCEPSS rescore
  32. 2026-05-31 00:14 UTCEPSS rescore
  33. 2026-05-28 13:42 UTCEPSS rescore
  34. 2026-05-28 13:42 UTCEPSS rescore
  35. 2026-05-22 21:15 UTCEPSS rescore
  36. 2026-05-22 21:15 UTCEPSS rescore
  37. 2026-05-22 20:27 UTCEG score recompute
  38. 2026-05-22 20:27 UTCVendor advisory
  39. 2026-05-22 20:27 UTCGHSA enrichment
  40. 2026-05-21 22:40 UTCEPSS rescore
  41. 2026-05-20 22:37 UTCEPSS rescore
  42. 2026-05-20 22:37 UTCEPSS rescore
  43. 2026-05-20 22:37 UTCEPSS rescore
  44. 2026-05-18 21:30 UTCEPSS rescore
  45. 2026-05-18 21:30 UTCEPSS rescore

Frequently asked(5)

What is CVE-2016-4553?
CVE-2016-4553 is a critical vulnerability published on May 10, 2016. 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.
When was CVE-2016-4553 disclosed?
CVE-2016-4553 was first published in the National Vulnerability Database on May 10, 2016, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-4553 actively exploited?
CVE-2016-4553 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 80% probability of exploitation in the next 30 days, which ranks it in the top 0.4% of all scored CVEs.
What is the CVSS score of CVE-2016-4553?
CVE-2016-4553 has a CVSS v3 base score of 8.6 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2016-4553?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-4553, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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