What’s Vulnerable › Vulnerabilities

CVE-2024-9398

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-10-01 · updated 2026-10-08
• Weakness: CWE-203

Description

By checking the result of calls to `window.open` with specifically set protocol handlers, an attacker could determine if the application which implements that protocol handler is installed. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131.

Affected products

• Mozilla Firefox: before 128.3.0; before 131.0 — fixed in 128.3.0, 131.0
• Mozilla Thunderbird: before 128.3; 129.0-beta, 129.0-beta2, 129.0-beta3, 129.0-beta4, 129.0-beta5, 129.0-beta6 — fixed in 128.3

How to fix

Upgrade to a fixed version: Mozilla Firefox 128.3.0, 131.0; Mozilla Thunderbird 128.3. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1881037
• https://www.mozilla.org/security/advisories/mfsa2024-46/
• https://www.mozilla.org/security/advisories/mfsa2024-47/
• https://www.mozilla.org/security/advisories/mfsa2024-49/
• https://www.mozilla.org/security/advisories/mfsa2024-50/

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