Is CVE-2012-5839 in the CISA KEV catalog?

No. CVE-2012-5839 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2012-5839?

CVE-2012-5839 has a CVSS v2 base score of 9.3 (HIGH).

What is the EPSS score for CVE-2012-5839?

CVE-2012-5839 has an EPSS score of 7.00% (93th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2012-5839?

Upgrade DeveloperEdition to 10.0.11 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2012-5839

HIGHEPSS 93th pctl

9.3

CVSS v2

NVD

Description

Heap-based buffer overflow in the gfxShapedWord::CompressedGlyph::IsClusterStart function in Mozilla Firefox before 17.0, Firefox ESR 10.x before 10.0.11, Thunderbird before 17.0, Thunderbird ESR 10.x before 10.0.11, and SeaMonkey before 2.14 allows remote attackers to execute arbitrary code via unspecified vectors.

CWE-787Out-of-bounds Write

How to fix

Remediation Available

DeveloperEditionWindows application

Affected:10.0.11Fixed in:10.0.11Mozilla

Affected:17.0Fixed in:17.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:10.0.11Fixed in:10.0.11Mozilla

Affected:17.0Fixed in:17.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:17.0Fixed in:17.0Mozilla

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

CVSS v2 Vector

No CVSS vector data available.

Exploit Intelligence

7.00%probability of exploitation in 30 days

93rdpercentile

High risk: more likely to be exploited than 93% of all known CVEs.

References

Related Vulnerabilities

Other CWE-787 (Out-of-bounds Write) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-22457	Critical	9.0	100%	KEV + Ransom	Fix
CVE-2025-0282	Critical	9.0	100%	KEV + Ransom	-
CVE-2015-3113	Critical	9.8	100%	KEV	Fix
CVE-2021-20038	Critical	9.8	100%	KEV + Ransom	-
CVE-2023-4863	High	8.8	100%	KEV	Fix
CVE-2020-16040	Medium	6.5	100%	-	Fix

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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 2026-04-29.