Mitigation bypass in the File Handling component

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Summary

CVECVE-2026-6763
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-21 13:16:22 UTC
Updated2026-04-22 17:38:00 UTC
DescriptionMitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS: 0.000400000 probability, percentile 0.122940000 (date 2026-04-22)

Problem Types: CWE-693 | CWE-693 CWE-693 Protection Mechanism Failure

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mozilla Firefox All All All All
Application Mozilla Firefox All All All All
Application Mozilla Thunderbird All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Firefox unaffected 140.10 140.* rpm Not specified
CNA Mozilla Firefox unaffected 150 * rpm Not specified
CNA Mozilla Thunderbird unaffected 140.10 140.* rpm Not specified
CNA Mozilla Thunderbird unaffected 150 * rpm Not specified

References

ReferenceSourceLinkTags
bugzilla.mozilla.org/show_bug.cgi [email protected] bugzilla.mozilla.org Permissions Required
www.mozilla.org/security/advisories/mfsa2026-34 [email protected] www.mozilla.org Vendor Advisory
www.mozilla.org/security/advisories/mfsa2026-30 [email protected] www.mozilla.org Vendor Advisory
www.mozilla.org/security/advisories/mfsa2026-32 [email protected] www.mozilla.org Vendor Advisory
www.mozilla.org/security/advisories/mfsa2026-33 [email protected] www.mozilla.org Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Tomoya Nakanishi (en)

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