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CVE-2025-5272VulnerabilityPublished Updated

CVE-2025-5272: Mozilla Firefox · Vulnerability

Affects Mozilla FirefoxSource CVE Database V5

0

Not known to be exploited · CVSS 7.3 High.

Data as of 26 Oct 2026, 07:57 UTC

CVSS 3.1 base score
7.3High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 May 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 2026-10-26.

What to do

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • =138
Fixed in–

AI-suggested

Users and administrators should update Firefox and Thunderbird to version 139 or later to remediate these vulnerabilities. The vendor advisory confirms that the issues are fixed in these versions. No additional mitigation steps are required beyond applying the official update.

Description

Memory safety bugs present in Firefox 138 and Thunderbird 138. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 139 and Thunderbird 139.

References

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