CVE-2025-6436HIGH 8.1EPSS p85.0%

CVE-2025-6436CVE-2025-6436

Description

Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

Scoring

CVSS 3.18.1 (HIGH)
VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS2.88% probability of exploitation · percentile 85.0% · 2026-06-19T12:03:05Z
Published2025-06-24
Last modified2026-04-13

Underlying weaknesses· 1

CWE-119

References

  1. https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C1966505%2C1970764%2C1942930
  2. https://www.mozilla.org/security/advisories/mfsa2025-51/
  3. https://www.mozilla.org/security/advisories/mfsa2025-54/

1

TypeTargetConfidenceTier
WeaknessImproper Restriction of Operations within the Bounds of a Memory Buffercwe-1190%live

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Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.