What’s Vulnerable › Vulnerabilities

CVE-2025-3029: URL Bar Spoofing via non-BMP Unicode characters

• Severity: high (CVSS 7.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-04-01 · updated 2026-10-05
• Weakness: CWE-290

Description

A crafted URL containing specific Unicode characters could have hidden the true origin of the page, resulting in a potential spoofing attack. This vulnerability was fixed in Firefox 137, Firefox ESR 128.9, Thunderbird 137, and Thunderbird 128.9.

Affected products

• Mozilla Firefox: before 128.9.0; before 137.0 — fixed in 128.9.0, 137.0
• Mozilla Thunderbird: before 128.9.0; from 129.0 before 137.0 — fixed in 128.9.0, 137.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 128.9.0, 137.0; Mozilla Thunderbird 128.9.0, 137.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1952213
• https://www.mozilla.org/security/advisories/mfsa2025-20/
• https://www.mozilla.org/security/advisories/mfsa2025-22/
• https://www.mozilla.org/security/advisories/mfsa2025-23/
• https://www.mozilla.org/security/advisories/mfsa2025-24/
• https://lists.debian.org/debian-lts-announce/2025/04/msg00005.html

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