CVE-2025-5269: Mozilla Firefox · Vulnerability
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 8.1 High · fixed in 128.11 : patch Mozilla Firefox soon.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 128.11
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 27 May 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in– |
AI-suggested
An official fix is available and has been released by Mozilla in Firefox ESR 128.11 and Thunderbird 128.11. Users and administrators should update to these versions or later to remediate this vulnerability. No additional mitigation actions are required beyond applying the official update.
Description
Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128.11 and Thunderbird 128.11.
References
- bugzilla.mozilla.org/show_bug.cgi?id=1924108 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-44/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-46/ (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00046.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00043.html (opens in a new tab)