CVE-2025-5263: Error handling for script execution was incorrectly isolated from web content, which could have
Source GCVE Database
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
- 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:NExploitation evidence
Disclosed: evidence found.
CVE published 27 May 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 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
- nvd.nist.gov/vuln/detail/CVE-2025-5263 (opens in a new tab)
- bugzilla.mozilla.org/show_bug.cgi?id=1960745 (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00043.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00046.html (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-42 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-43 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-44 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-45 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-46 (opens in a new tab)