Critical severity · published Jul 21, 2026
CVE-2026-16361
Memory safety bugs fixed in Thunderbird ESR 140.13
9.8
CVSS
0.6%
EPSS
No
On KEV
Description
Memory safety bugs present in Thunderbird ESR 140.12. 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 ESR 115.38, Firefox ESR 140.13, and Thunderbird 140.13.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 47% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
Firefox · Mozilla
before 115.38.0; 128.1.0 before 140.13.0 · source: NVD
TH
Thunderbird · Mozilla
before 140.13.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-16361
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-16361
Broken Link
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2029734%2C2036518
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-69/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-70/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-72/
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