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CVE-2025-49709VulnerabilityPublished Updated

CVE-2025-49709: Mozilla Firefox · Vulnerability

Affects Mozilla FirefoxSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical : upgrade to 139.0.4 as a priority.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 51% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 139.0.4
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 11 Jun 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 139.0.4.

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <139.0.4
Fixed in
  • 139.0.4

AI-suggested

Users and administrators should update Mozilla Firefox to version 139.0.4 or later to remediate this vulnerability. The vendor advisory confirms that the issue is fixed in this version. No additional mitigation steps are required beyond applying the official update.

Description

Certain canvas operations could have lead to memory corruption. This vulnerability was fixed in Firefox 139.0.4.

References

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