CVE-2025-1935: A web page could trick a user into setting that site as the default handler for a custom URL protocol
Source GCVE Database
Not known to be exploited · CVSS 4.3 Medium · fixed in 136 : update affected systems when convenient.
Data as of 30 Oct 2026, 01:15 UTC
- Patch
- Available – fixed in 136, 128.8
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 4 Mar 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 136 and Firefox ESR 128.8. Users and administrators should update to these versions or later to mitigate the issue. No additional action is required once updated, as the fix addresses the vulnerability directly.
Description
CVE-2025-1935 is a low-severity vulnerability in Firefox versions prior to 136 and Firefox ESR prior to 128.8. It allows a web page to trick a user into setting that site as the default handler for a custom URL protocol via clickjacking the registerProtocolHandler info-bar. This could lead to unintended protocol handling by the malicious site.
References
- nvd.nist.gov/vuln/detail/CVE-2025-1935 (opens in a new tab)
- bugzilla.mozilla.org/show_bug.cgi?id=1866661 (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/03/msg00006.html (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-14 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-16 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-17 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-18 (opens in a new tab)