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VulnerabilityPublished Updated

CVE-2025-1942: Mozilla Firefox · CWE-908

Affects Mozilla FirefoxSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical : upgrade to 136 as a priority.

Data as of 26 Oct 2026, 09:08 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
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 136
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 Mar 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 26 Oct 2026.

What to do

Upgrade Mozilla Firefox to 136.

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <136
Fixed in
  • 136

AI-suggested

Mozilla has fixed this vulnerability in Firefox 136 and Thunderbird 136. Users and administrators should update to these versions or later to remediate the issue. Since the vendor advisory confirms the fix is available, applying the official update is the recommended mitigation. No additional workarounds or mitigations are indicated by the vendor.

Description

When String.toUpperCase() caused a string to get longer it was possible for uninitialized memory to be incorporated into the result string. This vulnerability was fixed in Firefox 136 and Thunderbird 136.

References

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