CVE-2024-9399Public exploitNetwork attack vector

Process crash via WebTransport datagram thread race

Published Oct 1, 2024 · Updated Mar 14, 2025

Race condition in Mozilla Firefox before 131, Firefox ESR before 128.3, and Thunderbird before 131 allows remote attackers to crash the process. WebTransportSessionProxy can process an early datagram on the main thread after the session target moves to the socket thread, causing NotifyDatagramReceived to fail a release assertion. A website must induce the timing-sensitive session ordering; successful exploitation terminates the client process without reported data access or code execution.

CVSS severity7.5
High
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Race condition in Mozilla Firefox before 131, Firefox ESR before 128.3, and Thunderbird before 131 allows remote attackers to crash the process. WebTransportSessionProxy can process an early datagram on the main thread after the session target moves to the socket thread, causing NotifyDatagramReceived to fail a release assertion. A website must induce the timing-sensitive session ordering; successful exploitation terminates the client process without reported data access or code execution.

The record

CVE
CVE-2024-9399
Published
Oct 1, 2024
Updated
Mar 14, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-404, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 14, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <131

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <131
Mozilla · Thunderbirdversion=unspecified <128.3; version=unspecified <131
Mozilla · Firefox ESRversion=unspecified <128.3

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-404Improper Resource Shutdown or Release
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo