CVE-2026-113399: Incorrect Boundary Conditions
Source GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 158.0.1 : patch Firefox as a priority.
Data as of 29 Oct 2026, 20:15 UTC
Thin evidence
One scorer or none| CISA-ADP | CVSS 3.1 | 9.8 |
|---|
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 158.0.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 20 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
AI-suggested
Users and administrators should update affected Mozilla products to Firefox 158.0.1 and Thunderbird 158.0.1 or later, where this vulnerability has been fixed. No additional mitigation steps are required as the vendor has provided an official fix.
Description
CVE-2026-113399 is a critical vulnerability involving incorrect boundary conditions in the SVG component of Firefox and Thunderbird. This flaw could lead to severe impacts on confidentiality, integrity, and availability. The issue was fixed in Firefox 158.0.1 and Thunderbird 158.0.1. The vulnerability has a high CVSS score of 9.8, indicating critical severity. No known exploits in the wild have been reported.