CVE-2025-1935: firefox XSS — Fix

Description

A web page could trick a user into setting that site as the default handler for a custom URL protocol. This vulnerability was fixed in Firefox 136, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

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CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

Affected Products

Vendor	Product	Versions
mozilla	firefox	< 128.8.0
mozilla	firefox	< 136.0
mozilla	thunderbird	< 128.8.0
mozilla	thunderbird	129.0 — 136.0

References

Advisories & Patches

https://www.mozilla.org/security/advisories/mfsa2025-14/ https://www.mozilla.org/security/advisories/mfsa2025-16/ https://www.mozilla.org/security/advisories/mfsa2025-17/ https://www.mozilla.org/security/advisories/mfsa2025-18/

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=1866661 https://lists.debian.org/debian-lts-announce/2025/03/msg00006.html

Frequently Asked Questions

What is CVE-2025-1935? +

A web page could trick a user into setting that site as the default handler for a custom URL protocol. This vulnerability was fixed in Firefox 136, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2025-1935? +

CVE-2025-1935 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-1935? +

CVE-2025-1935 affects products from mozilla, specifically: firefox, thunderbird. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-1935? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2025-1935