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CVE-2026-0891

Memory safety bugs fixed in Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147

Published: Jan 13, 2026Updated: Apr 13, 2026 Sources: CVE List NVD BDUCWE-119
NVD MITRE
8.1CVSSHIGH
EPSS Score
0.4%
Top 69.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Memory safety bugs present in Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146 and Thunderbird 146. 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 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.

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
Red Hat Enterprise LinuxRed Hat Inc.
On-premOS
Operating Systems / linux-distro
openSUSE TumbleweedNovell Inc.
On-premOS
Operating Systems / linux-distro
Astra Linux Special EditionООО «РусБИТех-Астра»
On-premOS
Operating Systems / linux-distro
mozillaoss-projectUSConsumer Softwareaka mozilla corp.
red hat inc.commercialUSOperating Systemsaka red hat
novell inc.commercialUSOperating Systems
ооо «русбитех-астра»commercialRUOperating Systemsaka rusbitech-astra
and 10 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

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=1964722%2C2000981%2C2003100%2C2003278
bugzilla.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-01/
mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-03/
mozilla.org
and 12 more references View all →

Timeline

Published
Jan 13, 2026
Last Updated
Apr 13, 2026

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