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CVE-2026-12327

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

Published: Jun 16, 2026Updated: Jun 17, 2026 Sources: CVE List NVDCWE-119
NVD MITRE
8.1CVSSHIGH
EPSS Score
0.3%
Top 79.7%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Memory 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.

CVSS Vector Breakdown

AV:NAC:HPR:NUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-119

Affected Products

firefoxmozilla
On-premDesktop App
Consumer Software / browser
thunderbirdmozilla
On-premDesktop App
Communications / email-server-client
FirefoxMozilla
On-premDesktop App
Consumer Software / browser
ThunderbirdMozilla
On-premDesktop App
Communications / email-server-client
mozillaoss-projectUSConsumer Softwareaka mozilla corp.

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=2011842%2C2023902%2C2025512%2C2027312%2C2029444%2C2036571%2C2036900%2C2036936%2C2037995%2C2038551%2C2040717%2C2042724
bugzilla.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-57/
mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-58/
mozilla.org
and 2 more references View all →

Timeline

Published
Jun 16, 2026
Last Updated
Jun 17, 2026
News mentions
1

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