No exploitation reported

CVE-2026-109708

Sandbox escape due to incorrect boundary conditions in the Networking component

No exploitation reported by the sources we read.

Published2026-10-13
WeaknessCWE-119

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

Timeline

dates in UTC

2026-10-1313:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-109708?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-109708?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-109708 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVE recordread 2026-10-23
CISA-ADPSSVC decisionnone2026-10-15
OpenCVESSVC decisionnone—
CISA-ADPCVSS 3.19.62026-10-15
CISA-ADPweakness (CWE)CWE-1192026-10-15
FIRST EPSSEPSS score0.3 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Published: 2026-10-13
Last Modified: 2026-10-15
NVD status: Deferred

Frequently asked questions

What is CVE-2026-109708?

Sandbox escape due to incorrect boundary conditions in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

Is CVE-2026-109708 actively exploited?

Active exploitation of CVE-2026-109708 has not been confirmed. Its EPSS score was 0.3% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-109708?

CVE-2026-109708 has a CVSS v3 base score of 9.6 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

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