Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-84145
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-01 13:20:08 UTC
Updated2026-09-01 22:17:18 UTC
DescriptionInternally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

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

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

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Firefox unaffected 115.40 115.* rpm Not specified
CNA Mozilla Firefox unaffected 140.15 140.* rpm Not specified
CNA Mozilla Firefox unaffected 153.2 153.* rpm Not specified
CNA Mozilla Firefox unaffected 155 * rpm Not specified
CNA Mozilla Thunderbird unaffected 140.15 140.* rpm Not specified
CNA Mozilla Thunderbird unaffected 153.2 153.* rpm Not specified
CNA Mozilla Thunderbird unaffected 155 * rpm Not specified

References

ReferenceSourceLinkTags
bugzilla.mozilla.org/buglist.cgi [email protected] bugzilla.mozilla.org
bugzilla.mozilla.org/buglist.cgi [email protected] bugzilla.mozilla.org
bugzilla.mozilla.org/show_bug.cgi [email protected] bugzilla.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-88 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-85 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-84 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-87 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-86 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-82 [email protected] www.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-83 [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: Leo Tenenbaum, Tom Ritter and the Mozilla Fuzzing Team (en)

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