CVE-2025-3859: firefox focus Open Redirect — Fix

Description

Websites directing users to long URLs that caused eliding to occur in the location view could leverage the truncating behavior to potentially trick users into thinking they were on a different webpage. This vulnerability was fixed in Focus 138.

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CVSS v3.1 Score

6.1

MEDIUM

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

Weakness Type (CWE)

CWE-601 CWE-601

CWE-451 CWE-451

Affected Products

Vendor	Product	Versions
mozilla	firefox_focus	< 138.0

References

Advisories & Patches

https://www.mozilla.org/security/advisories/mfsa2025-33/

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=1951533

Frequently Asked Questions

What is CVE-2025-3859? +

Websites directing users to long URLs that caused eliding to occur in the location view could leverage the truncating behavior to potentially trick users into thinking they were on a different webpage. This vulnerability was fixed in Focus 138. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2025-3859? +

CVE-2025-3859 has a CVSS v3.1 score of 6.1 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-2025-3859? +

CVE-2025-3859 affects products from mozilla, specifically: firefox_focus. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-3859? +

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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