Medium severity · published Jun 16, 2026
CVE-2026-12329
Memory safety bug fixed in Thunderbird ESR 140.12
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
Memory safety bug fixed in Thunderbird ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12 and Thunderbird 140.12.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
Firefox · Mozilla
140.0 before 140.12.0 · source: NVD
TH
Thunderbird · Mozilla
140.0 before 140.12.0 · source: NVD
RH
Red Hat Enterprise Linux 10 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 10.0 Extended Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 6 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 7 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 7 Extended Lifecycle Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-12329
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-12329
Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=2044738
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-58/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-61/
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:27717
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:27733
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:27734
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