CVE-2025-49709: Mozilla Firefox · Vulnerability
Affects Mozilla FirefoxSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 11 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
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.