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VulnerabilityPublished Updated

CVE-2026-113399: Incorrect Boundary Conditions

Source GCVE Database

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Authoritative record:CVE-2026-113399· Critical 9.8

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

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.19.8
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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.

References

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