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CVE-2025-1009VulnerabilityPublished Updated

CVE-2025-1009: Mozilla Firefox · Vulnerability

Affects Mozilla FirefoxSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical : upgrade to 135 as a priority.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.2% chance of exploitation in 30 days – higher than 68% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 135
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 4 Feb 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 2026-10-25.

What to do

Upgrade Mozilla Firefox to 135.

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <135
Fixed in
  • 135

AI-suggested

Mozilla has released official patches fixing this vulnerability in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135. Users and administrators should update to these versions or later to remediate the vulnerability. Since this is not a cloud service, remediation depends on applying these updates. Patch status is confirmed by the vendor advisory.

Description

An attacker could have caused a use-after-free via crafted XSLT data, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

References

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