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VulnerabilityPublished Updated

CVE-2026-100808: Mozilla Firefox · CWE-693

Affects Mozilla FirefoxSource CVE Database V5

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Not known to be exploited · CVSS 8.8 High · fixed in 153.4 : patch Mozilla Firefox soon.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 153.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 Sep 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 13 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <153.4
Fixed in
  • 153.4

AI-suggested

Users should update to Firefox ESR 153.4 or Firefox 157, or Thunderbird 153.4 or 157, where this vulnerability has been fixed. No additional mitigation is required once the update is applied. There are no known exploits in the wild at this time.

Description

CVE-2026-100808 is a high-severity vulnerability in Mozilla Firefox affecting the DOM: Service Workers component that allows mitigation bypass. This flaw was addressed in Firefox ESR 153.4 and Firefox 157, as well as Thunderbird versions 153.4 and 157. The vulnerability has a CVSS score of 8.8, indicating a critical impact on confidentiality, integrity, and availability. No known exploits are currently reported in the wild.

References

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