CVE-2016-4979

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2022-05-13. NVD baseline CVSS 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 19%CVSS: 7.5Exploit: Elevated riskExposed: 0

A fix is available — apply it.

The Apache HTTP Server 2.4.18 through 2.4.20, when mod_http2 and mod_ssl are enabled, does not properly recognize the "SSLVerifyClient require" directive for HTTP/2 request authorization, which allows remote attackers to bypass intended access restrictions by leveraging the ability to send multiple requests over a single connection and aborting a renegotiation.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
54(Track)
EG Risk 54/100SSVC: 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
Severity75% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
19%
EPSS %ILE
97%
KEV
Not listed

Published

July 6, 2016

Last Modified

June 17, 2026

References (50)

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhathttpd24-httpd-0:2.4.18-11.el72016-07-18redhat

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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.23-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.23-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.23-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
apache2—2.4.23-1—

Weakness Classification(1)

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

All Vendor Advisories

(1)

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 5× in last 7d / 16× 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.

Showing the most recent 100 of 137 total refreshes for this CVE.

  1. 2026-09-19 15:35 UTCEPSS rescore
  2. 2026-09-18 23:30 UTCOSV refresh
  3. 2026-09-18 19:22 UTCEPSS rescore
  4. 2026-09-17 19:21 UTCEPSS rescore
  5. 2026-09-15 03:05 UTCEPSS rescore
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  10. 2026-09-01 03:31 UTCEPSS rescore
  11. 2026-08-31 03:02 UTCOSV refresh
  12. 2026-08-30 19:12 UTCEPSS rescore
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  23. 2026-08-14 11:15 UTCOSV refresh
  24. 2026-08-12 13:46 UTCEPSS rescore
  25. 2026-08-11 13:36 UTCEPSS rescore
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  1. 2026-08-09 13:42 UTCEPSS rescore
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  9. 2026-07-30 16:23 UTCEPSS rescore
  10. 2026-07-29 22:07 UTCOSV refresh
  11. 2026-07-28 15:31 UTCEPSS rescore
  12. 2026-07-26 14:50 UTCEPSS rescore
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  14. 2026-07-23 14:14 UTCEPSS rescore
  15. 2026-07-23 01:23 UTCEG score recompute
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  20. 2026-07-20 17:03 UTCEPSS rescore
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  23. 2026-07-18 10:00 UTCEPSS rescore
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  25. 2026-07-16 16:59 UTCEPSS rescore
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  27. 2026-07-15 16:54 UTCEPSS rescore
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  29. 2026-07-15 01:56 UTCEPSS rescore
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  31. 2026-07-13 22:26 UTCEPSS rescore
  32. 2026-07-13 06:09 UTCEPSS rescore
  33. 2026-07-12 09:07 UTCOSV refresh
  34. 2026-07-12 05:43 UTCEPSS rescore
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  36. 2026-07-11 08:23 UTCEPSS rescore
  37. 2026-07-09 19:05 UTCEPSS rescore
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  39. 2026-07-07 13:42 UTCEPSS rescore
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  42. 2026-07-05 02:27 UTCEPSS rescore
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  44. 2026-07-01 15:02 UTCEPSS rescore
  45. 2026-06-30 23:19 UTCEPSS rescore
  46. 2026-06-28 14:04 UTCEPSS rescore
  47. 2026-06-28 04:53 UTCEPSS rescore
  48. 2026-06-27 03:05 UTCEPSS rescore
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  50. 2026-06-25 13:47 UTCEPSS rescore
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  52. 2026-06-24 14:02 UTCEPSS rescore
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  54. 2026-06-23 21:30 UTCEPSS rescore
  55. 2026-06-23 14:30 UTCOSV refresh
  56. 2026-06-22 14:23 UTCEPSS rescore
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  61. 2026-06-19 19:23 UTCEPSS rescore
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  63. 2026-06-18 17:50 UTCEPSS rescore
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  74. 2026-06-11 13:57 UTCEPSS rescore
  75. 2026-06-10 22:15 UTCEPSS rescore

Frequently asked(5)

What is CVE-2016-4979?
CVE-2016-4979 is a high vulnerability published on July 6, 2016. The Apache HTTP Server 2.4.18 through 2.4.20, when modhttp2 and modssl are enabled, does not properly recognize the "SSLVerifyClient require" directive for HTTP/2 request authorization, which allows remote attackers to bypass intended access restrictions by leveraging the ability to send multiple…
When was CVE-2016-4979 disclosed?
CVE-2016-4979 was first published in the National Vulnerability Database on July 6, 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-2016-4979 actively exploited?
CVE-2016-4979 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 19% probability of exploitation in the next 30 days, which ranks it in the top 2.9% of all scored CVEs.
What is the CVSS score of CVE-2016-4979?
CVE-2016-4979 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2016-4979?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-4979, 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.

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