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VulnerabilityPublished Updated

CVE-2025-2857: Mozilla Firefox · Resource Exposure

Affects Mozilla FirefoxSource CVE Database V5

0

Mentioned vulnerabilities

Not known to be exploited · CVSS 10.0 Critical : upgrade to 136.0.4 as a priority.

Data as of 26 Oct 2026, 09:08 UTC

CVSS 3.1 base score
10.0Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.9% chance of exploitation in 30 days – higher than 80% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 136.0.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 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 136.0.4.

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <136.0.4
Fixed in
  • 136.0.4

AI-suggested

This vulnerability is fixed in Firefox 136.0.4, Firefox ESR 128.8.1, and Firefox ESR 115.21.1. Users and administrators should update affected Firefox installations to these versions or later to remediate the issue. No other mitigation is required as the fix is official and available.

Description

Following the recent Chrome sandbox escape (CVE-2025-2783), various Firefox developers identified a similar pattern in our IPC code. A compromised child process could cause the parent process to return an unintentionally powerful handle, leading to a sandbox escape. The original vulnerability was being exploited in the wild. *This only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability was fixed in Firefox 136.0.4, Firefox ESR 128.8.1, and Firefox ESR 115.21.1.

References

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