All vulnerabilities
CVE-2026-109708

Firefox: Sandbox escape due to incorrect boundary conditions in the Networking component

Mozilla FirefoxApplications & CMS
Open in ThreatlineRecord JSON
CVSS
9.6Critical
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.32%Chance of exploitation activity in the next 30 days, higher than 23% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published13 Oct 2026Updated 15 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

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.

Text from CVE List

Affected versions 4

  • Firefoxunaffected: 153.5 through 153.*CVE List
  • Firefoxunaffected: 158CVE List
  • Thunderbirdunaffected: 153.5 through 153.*CVE List
  • Thunderbirdunaffected: 158CVE List

References 5