CVE-2016-5256

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-17. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 4%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 49.0 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unknown vectors.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: 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
Severity98% × 45%
Exploitation4% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
89.0%
KEV
Not listed

Published

September 22, 2016

Last Modified

May 6, 2026

Advisory Details (8)

Auto-updated May 9, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic

1297099 - LoadManagerSingleton weak reference used on multiple threads

https://bugzilla.mozilla.org/show_bug.cgi?id=1297099
generic🔴 Active Exploitation

1296087 - IonCache getter stub may not correctly restore clobbered register

https://bugzilla.mozilla.org/show_bug.cgi?id=1296087
generic

1296078 - format string mismatch in CreateDXVAManagerEvent::Run()

https://bugzilla.mozilla.org/show_bug.cgi?id=1296078
generic

1290244 - Crash: double-free [@xcb_render_create_picture]

https://bugzilla.mozilla.org/show_bug.cgi?id=1290244
generic

1282746 - Assertion failure: comp == compartment || runtime()->isAtomsCompartment(comp) || (srcKind == JS::TraceKind::Object && InCrossCompartmentMap(static_cast<JSObject*>(src), thing)), at js/src/jsgc.cpp:3745

https://bugzilla.mozilla.org/show_bug.cgi?id=1282746
generic

1276413 - Clear the buffer we allocate for paletted image frames

https://bugzilla.mozilla.org/show_bug.cgi?id=1276413
generic

1268034 - Assertion failure: isObject(), at dist/include/js/Value.h:1281

https://bugzilla.mozilla.org/show_bug.cgi?id=1268034
generic
http://www.securityfocus.com/bid/93052

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntufirefox-testsuite (49.0+build4-0ubuntu0.16.04.1) @ xenial2026-05-20ubuntu

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.

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 10× in last 7d / 38× 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 114 total refreshes for this CVE.

  1. 2026-07-23 14:14 UTCEPSS rescore
  2. 2026-07-23 01:23 UTCEG score recompute
  3. 2026-07-22 22:02 UTCEG score recompute
  4. 2026-07-22 14:04 UTCEPSS rescore
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  19. 2026-07-13 22:26 UTCEPSS rescore
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  22. 2026-07-11 08:23 UTCEPSS rescore
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  24. 2026-07-08 15:10 UTCEPSS rescore
  25. 2026-07-07 13:42 UTCEPSS rescore
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  1. 2026-07-06 16:24 UTCEPSS rescore
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  5. 2026-07-05 02:27 UTCEPSS rescore
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  8. 2026-06-30 23:19 UTCEPSS rescore
  9. 2026-06-28 04:53 UTCEPSS rescore
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  12. 2026-06-25 13:47 UTCEPSS rescore
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  16. 2026-06-23 21:30 UTCEPSS rescore
  17. 2026-06-21 14:54 UTCEPSS rescore
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  19. 2026-06-21 01:57 UTCEPSS rescore
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  21. 2026-06-18 17:50 UTCEPSS rescore
  22. 2026-06-17 17:50 UTCEPSS rescore
  23. 2026-06-17 17:50 UTCEPSS rescore
  24. 2026-06-16 17:50 UTCEPSS rescore
  25. 2026-06-16 17:50 UTCEPSS rescore
  26. 2026-06-15 17:45 UTCEPSS rescore
  27. 2026-06-14 23:14 UTCEPSS rescore
  28. 2026-06-13 22:57 UTCEPSS rescore
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  30. 2026-06-12 23:09 UTCEPSS rescore
  31. 2026-06-12 23:09 UTCEPSS rescore
  32. 2026-06-11 13:57 UTCEPSS rescore
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  35. 2026-06-08 14:14 UTCEPSS rescore
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  40. 2026-06-05 06:08 UTCEPSS rescore
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  42. 2026-06-04 13:10 UTCEPSS rescore
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  44. 2026-06-02 20:10 UTCEPSS rescore
  45. 2026-06-01 13:49 UTCEPSS rescore
  46. 2026-06-01 13:49 UTCEPSS rescore
  47. 2026-05-31 22:28 UTCEPSS rescore
  48. 2026-05-31 22:28 UTCEPSS rescore
  49. 2026-05-31 00:14 UTCEPSS rescore
  50. 2026-05-29 13:41 UTCEPSS rescore
  51. 2026-05-28 13:42 UTCEPSS rescore
  52. 2026-05-28 13:42 UTCEPSS rescore
  53. 2026-05-27 13:38 UTCEPSS rescore
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  66. 2026-05-20 11:21 UTCEPSS rescore
  67. 2026-05-20 10:23 UTCVendor advisory
  68. 2026-05-20 10:23 UTCGHSA enrichment
  69. 2026-05-20 06:44 UTCVendor advisory
  70. 2026-05-20 06:44 UTCGHSA enrichment
  71. 2026-05-20 03:05 UTCVendor advisory
  72. 2026-05-20 03:05 UTCGHSA enrichment
  73. 2026-05-19 23:25 UTCVendor advisory
  74. 2026-05-19 23:25 UTCGHSA enrichment
  75. 2026-05-19 19:46 UTCVendor advisory

Frequently asked(5)

What is CVE-2016-5256?
CVE-2016-5256 is a critical vulnerability published on September 22, 2016. Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 49.0 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unknown vectors.
When was CVE-2016-5256 disclosed?
CVE-2016-5256 was first published in the National Vulnerability Database on September 22, 2016, with the most recent update on May 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-5256 actively exploited?
CVE-2016-5256 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 89.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2016-5256?
CVE-2016-5256 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2016-5256?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-5256, 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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