Critical severity · published Oct 20, 2026
CVE-2026-113399
Incorrect boundary conditions in the SVG component
9.8
CVSS
0.2%
EPSS
No
On KEV
Description
Incorrect boundary conditions in the SVG component. This vulnerability was fixed in Firefox 158.0.1 and Thunderbird 158.0.1.
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)0.2% · higher than 7% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-113399
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-113399
bugzilla.mozilla.org
https://bugzilla.mozilla.org/show_bug.cgi?id=2079938
www.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-111/
www.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-114/