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VulnerabilityPublished Updated

CVE-2025-10534: Mozilla Firefox · Cross-site Scripting

Affects Mozilla FirefoxSource CVE Database V5

0

Not known to be exploited · CVSS 8.1 High : upgrade to 143 soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 143
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Sep 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade Mozilla Firefox to 143.

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <143
Fixed in
  • 143

AI-suggested

Mozilla has released official fixes for this vulnerability in Firefox 143 and Thunderbird 143. Users and administrators should update affected products to these versions or later to mitigate the risk. No additional mitigation steps are indicated by the vendor advisory.

Description

Spoofing issue in the Site Permissions component. This vulnerability was fixed in Firefox 143 and Thunderbird 143.

References

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