CVE-2024-9399

Name: CVE-2024-9399
Creator: NVD / NIST
Published: 2024-10-01T16:15:10.98+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.50%

Last modified Jun 17, 2026

CVE-2024-9399 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 0.50% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.50%

38.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-404

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 128.3.0
Mozilla	Firefox	>= 129.0, < 131.0
Mozilla	Thunderbird	< 128.3.0
Mozilla	Thunderbird	>= 129.0, < 131.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1907726Issue Tracking, Permissions Required
https://www.mozilla.org/security/advisories/mfsa2024-46/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-47/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-49/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2024-50/Vendor Advisory

Timeline

Published: Oct 1, 2024
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2024-9399?

How severe is CVE-2024-9399?

CVE-2024-9399 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.50% probability of exploitation in the next 30 days.

How do I fix CVE-2024-9399?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2024-9399?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST