Is CVE-2016-2821 in the CISA KEV catalog?

No. CVE-2016-2821 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2016-2821?

CVE-2016-2821 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2016-2821?

CVE-2016-2821 has an EPSS score of 2.78% (85th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2016-2821?

Upgrade firefox on debian unstable to 47.0-1 or later. Fixes are available for 2 affected products.

CVE & CISA-KEV Catalog

CVE-2016-2821

HIGHEPSS 85th pctl

7.5

CVSS v3

NVD

Description

Use-after-free vulnerability in the mozilla::dom::Element class in Mozilla Firefox before 47.0 and Firefox ESR 45.x before 45.2, when contenteditable mode is enabled, allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) by triggering deletion of DOM elements that were created in the editor.

How to fix

Remediation Available

firefoxDebian

Fixed in:47.0-1CVE-2016-2821

firefoxUbuntu

Fixed in:47.0+build3-0ubuntu0.14.04.1USN-2993-1

Fixed in:47.0+build3-0ubuntu0.16.04.1USN-2993-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploit Intelligence

2.78%probability of exploitation in 30 days

85thpercentile

Elevated risk: more likely to be exploited than 85% of all known CVEs.

References

Vendor Advisory1

mozilla.org

Other references10

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-06.