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CVE-2024-9399

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-10-01 · updated 2026-06-17
• Weakness: CWE-404

Description

A website configured to initiate a specially crafted WebTransport session could crash the Firefox process leading to a denial of service condition. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131.

Affected products

• Mozilla Firefox: before 128.3.0; from 129.0 before 131.0 — fixed in 128.3.0, 131.0
• Mozilla Thunderbird: before 128.3.0; from 129.0 before 131.0 — fixed in 128.3.0, 131.0

How to fix

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

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1907726
• 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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