CVE-2016-8740

HIGHNVD 7.58.8▲
EchelonGraph scoreHIGH confidence

Score elevated to 8.8 because EPSS predicts 79% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs). NVD baseline CVSS 7.5 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, ghsa, nvd
Elevated
8.8EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • 57 internet-facing services (distinct ip:port) on record running an affected version — derived from Shodan data (© Shodan); a patched service can stay counted while its port stays open
  • High exploitation likelihood — EPSS 79%
CISA-KEV: Not listedEPSS PROB: 79%CVSS: 7.5Exploit: Elevated riskExposed services: 57

A fix is available — apply it.

The mod_http2 module in the Apache HTTP Server 2.4.17 through 2.4.23, when the Protocols configuration includes h2 or h2c, does not restrict request-header length, which allows remote attackers to cause a denial of service (memory consumption) via crafted CONTINUATION frames in an HTTP/2 request.

Internet exposure · derived from Shodan data

57 internet-facing services (distinct ip:port) on record running a version that maps to CVE-2016-8740, in our KEV-Exposure radar’s Shodan-derived sample.

across 19 countries (United States, Germany, France, Ireland, Singapore)top: http_server
See the KEV-Exposure radar →Derived from Shodan data. Shodan data is owned by Shodan, which holds its copyright (© Shodan). EchelonGraph claims no ownership of it or copyright in it. Aggregate, host-redacted.

How it counts: every 12 hours, when Shodan query credits allow, the radar runs one Shodan query per tracked product, reads up to 100 ip:port services per query, and keeps a service when its banner version matches a CISA-KEV or high-EPSS CVE; a service is dropped when neither a search nor a Shodan InternetDB port re-check has refreshed it for 21 days. A re-check that finds the port still listed by Shodan InternetDB refreshes the service without re-reading the banner, so a patched service can stay counted while its port stays open. A count is a banner-version inference over a sample, not an exploit test and not an internet-wide census, and the unit is a service, not a machine: a machine answering on two ports counts twice.

CVSS v3
7.5
EG Score
8.8HIGHhigh confidence
EG Risk
76
EG Risk 76/100CISA SSVC

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
Severity88% × 45%
Exploitation79% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track* or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
79%
EPSS %ILE
99th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (EG-KEV: elevated) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

December 5, 2016

Last Modified

June 17, 2026

References (56)

Vendor Advisories for CVE-2016-8740(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(4)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatjbcs-httpd24-openssl-1:1.0.2h-13.jbcs.el62017-06-07redhat
redhatjbcs-httpd24-openssl-1:1.0.2h-13.jbcs.el72017-06-07redhat
redhatpatch2017-06-07redhat
redhathttpd24-httpd-0:2.4.25-9.el72017-04-26redhat

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 rangeFix by version rangeDependents
apache2—
  • every version up to 2.4.25-1: fixed in 2.4.25-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
apache2—
  • every version up to 2.4.25-1: fixed in 2.4.25-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
apache2—
  • every version up to 2.4.25-1: fixed in 2.4.25-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
apache2—
  • every version up to 2.4.25-1: fixed in 2.4.25-1
—

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 4× in last 7d / 14× 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. 2026-10-03 14:21 UTCEPSS rescore
  2. 2026-10-03 14:21 UTCEPSS rescore
  3. 2026-09-30 14:58 UTCEPSS rescore
  4. 2026-09-30 09:17 UTCEG score recompute
  5. 2026-09-24 13:59 UTCEPSS rescore
  6. 2026-09-23 13:41 UTCEPSS rescore
  7. 2026-09-20 20:09 UTCEPSS rescore
  8. 2026-09-18 19:22 UTCEPSS rescore
  9. 2026-09-18 18:20 UTCOSV refresh
  10. 2026-09-15 03:05 UTCEPSS rescore
  11. 2026-09-12 14:55 UTCEPSS rescore
  12. 2026-09-11 14:46 UTCEPSS rescore
  13. 2026-09-10 09:26 UTCEPSS rescore
  14. 2026-09-07 15:56 UTCEPSS rescore
  15. 2026-09-04 13:56 UTCEPSS rescore
  16. 2026-09-01 13:48 UTCEPSS rescore
  17. 2026-08-30 21:34 UTCOSV refresh
  18. 2026-08-28 21:35 UTCEPSS rescore
  19. 2026-08-26 14:41 UTCEPSS rescore
  20. 2026-08-25 13:44 UTCEPSS rescore
  21. 2026-08-21 23:44 UTCEPSS rescore
  22. 2026-08-19 16:59 UTCEPSS rescore
  23. 2026-08-16 02:10 UTCEPSS rescore
  24. 2026-08-14 08:16 UTCOSV refresh
  25. 2026-08-11 13:36 UTCEPSS rescore
Show 72 more
  1. 2026-08-04 15:05 UTCEPSS rescore
  2. 2026-07-30 16:24 UTCEPSS rescore
  3. 2026-07-30 01:26 UTCEPSS rescore
  4. 2026-07-30 01:26 UTCEPSS rescore
  5. 2026-07-29 16:37 UTCOSV refresh
  6. 2026-07-26 14:50 UTCEPSS rescore
  7. 2026-07-25 14:13 UTCEPSS rescore
  8. 2026-07-24 14:13 UTCEPSS rescore
  9. 2026-07-23 01:24 UTCEG score recompute▲ 1.30
  10. 2026-07-22 22:04 UTCEG score recompute
  11. 2026-07-22 14:04 UTCEPSS rescore
  12. 2026-07-21 15:21 UTCEPSS rescore
  13. 2026-07-21 15:21 UTCEPSS rescore
  14. 2026-07-19 14:28 UTCEPSS rescore
  15. 2026-07-19 14:28 UTCEPSS rescore
  16. 2026-07-16 16:59 UTCEPSS rescore
  17. 2026-07-16 16:59 UTCEPSS rescore
  18. 2026-07-15 16:54 UTCEPSS rescore
  19. 2026-07-15 16:54 UTCEPSS rescore
  20. 2026-07-13 22:26 UTCEPSS rescore
  21. 2026-07-12 06:07 UTCOSV refresh
  22. 2026-07-11 08:24 UTCEPSS rescore
  23. 2026-07-08 15:10 UTCEPSS rescore
  24. 2026-07-04 06:28 UTCEPSS rescore
  25. 2026-07-01 15:02 UTCEPSS rescore
  26. 2026-06-27 03:05 UTCEPSS rescore
  27. 2026-06-25 13:47 UTCEPSS rescore
  28. 2026-06-23 21:30 UTCEPSS rescore
  29. 2026-06-23 11:58 UTCOSV refresh
  30. 2026-06-21 14:54 UTCEPSS rescore
  31. 2026-06-21 14:54 UTCEPSS rescore
  32. 2026-06-21 01:57 UTCEPSS rescore
  33. 2026-06-21 01:57 UTCEPSS rescore
  34. 2026-06-18 17:50 UTCEPSS rescore
  35. 2026-06-18 17:50 UTCEPSS rescore
  36. 2026-06-17 17:50 UTCEPSS rescore
  37. 2026-06-17 17:50 UTCEPSS rescore
  38. 2026-06-15 17:45 UTCEPSS rescore
  39. 2026-06-14 23:14 UTCEPSS rescore
  40. 2026-06-14 23:14 UTCEPSS rescore
  41. 2026-06-12 23:09 UTCEPSS rescore
  42. 2026-06-11 13:57 UTCEPSS rescore
  43. 2026-06-08 14:14 UTCEPSS rescore
  44. 2026-06-07 15:22 UTCEPSS rescore
  45. 2026-06-07 15:22 UTCEPSS rescore
  46. 2026-06-06 13:45 UTCEPSS rescore
  47. 2026-06-06 13:45 UTCEPSS rescore
  48. 2026-06-06 13:44 UTCOSV refresh
  49. 2026-06-05 06:08 UTCEPSS rescore
  50. 2026-06-05 06:08 UTCEPSS rescore
  51. 2026-06-01 13:49 UTCEPSS rescore
  52. 2026-06-01 13:49 UTCEPSS rescore
  53. 2026-05-31 22:28 UTCEPSS rescore
  54. 2026-05-31 22:28 UTCEPSS rescore
  55. 2026-05-31 00:14 UTCEPSS rescore
  56. 2026-05-29 13:41 UTCEPSS rescore
  57. 2026-05-28 13:42 UTCEPSS rescore
  58. 2026-05-28 13:42 UTCEPSS rescore
  59. 2026-05-27 13:38 UTCEPSS rescore
  60. 2026-05-27 13:38 UTCEPSS rescore
  61. 2026-05-26 13:42 UTCEPSS rescore
  62. 2026-05-26 13:42 UTCEPSS rescore
  63. 2026-05-22 21:15 UTCEPSS rescore
  64. 2026-05-22 17:46 UTCEG score recompute
  65. 2026-05-22 17:46 UTCVendor advisory
  66. 2026-05-22 17:46 UTCGHSA enrichment
  67. 2026-05-20 22:37 UTCEPSS rescore
  68. 2026-05-20 22:37 UTCEPSS rescore
  69. 2026-05-20 22:37 UTCEPSS rescore
  70. 2026-05-18 21:30 UTCEPSS rescore
  71. 2026-05-18 21:30 UTCEPSS rescore
  72. 2026-05-18 21:30 UTCEPSS rescore

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-40909
    First seen Dec 12, 2016

    Apache 2.4.23 mod_http2 - Denial of Service

    Open source ↗

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2016-8740?
CVE-2016-8740 is a high vulnerability published on December 5, 2016. The mod_http2 module in the Apache HTTP Server 2.4.17 through 2.4.23, when the Protocols configuration includes h2 or h2c, does not restrict request-header length, which allows remote attackers to cause a denial of service (memory consumption) via crafted CONTINUATION frames in an HTTP/2 request.
When was CVE-2016-8740 disclosed?
CVE-2016-8740 was first published on December 5, 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-2016-8740 actively exploited?
CVE-2016-8740 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 79% probability of exploitation in the next 30 days (99th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2016-8740?
CVE-2016-8740 has a CVSS v3 base score of 7.5 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.8 (HIGH).
How do I remediate CVE-2016-8740?
A fix for CVE-2016-8740 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2016-8740 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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