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VulnerabilityPublished Updated

CVE-2025-5263: Error handling for script execution was incorrectly isolated from web content, which could have

Source GCVE Database

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Authoritative record:CVE-2025-5263· Medium 4.3

Not known to be exploited · CVSS 4.3 Medium · fixed in 139 : update affected systems when convenient.

Data as of 30 Oct 2026, 01:42 UTC

CVSS 3.1 base score
4.3Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 139, 128.11, 115.24
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 May 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: 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 29 Oct 2026.

What to do

AI-suggested

This vulnerability is fixed in Firefox 139 and Firefox ESR 115.24 and 128.11. Users and administrators should update affected Firefox installations to these versions or later to remediate the issue. No additional mitigation actions are required beyond applying the official updates.

Description

CVE-2025-5263 is a moderate severity vulnerability in Firefox where error handling for script execution was not properly isolated from web content, potentially allowing cross-origin information leak attacks. This issue affects Firefox versions prior to 139 and Firefox ESR versions prior to 115.24 and 128.11. The vulnerability has been fixed in Firefox 139 and Firefox ESR 115.24 and 128.11.

References

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