Memory safety bugs fixed in Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152

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Summary

CVECVE-2026-12327
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-16 13:16:33 UTC
Updated2026-06-16 17:16:38 UTC
DescriptionMemory safety bugs present in Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151. 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 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

Risk And Classification

Primary CVSS: v3.1 7.3 HIGH from ADP

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

Problem Types: CWE-119 | CWE-119 CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.3HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.3HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Firefox unaffected 140.12 140.* rpm Not specified
CNA Mozilla Firefox unaffected 152 * rpm Not specified
CNA Mozilla Thunderbird unaffected 140.12 140.* rpm Not specified
CNA Mozilla Thunderbird unaffected 152 * rpm Not specified

References

ReferenceSourceLinkTags
www.mozilla.org/security/advisories/mfsa2026-58 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-57 [email protected] www.mozilla.org
bugzilla.mozilla.org/buglist.cgi [email protected] bugzilla.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-61 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-60 [email protected] www.mozilla.org
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: Christian Holler, Jens Stutte, Nika Layzell, Randell Jesup, Tom Schuster and the Mozilla Fuzzing Team (en)

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