CVE-2025-1931Public exploitNetwork attack vector

Content-process crash via WebTransportChild use-after-free

Published Mar 4, 2025 · Updated Apr 13, 2026

Use-after-free in Mozilla Firefox and Thunderbird allows remote attackers to crash a content process through a WebTransport connection. WebTransportChild retains its WebTransport owner through a raw mTransport pointer, and RecvRemoteClosed calls Cleanup, where promise resolution can dispatch an event that releases the owner before processing completes. Reachability requires remote-close cleanup; affected lines are Firefox before 136, Firefox ESR before 115.21 or 128.8, and Thunderbird before 128.8 or 136.

CVSS severity7.5
High
EPSS probability0.53%
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

Use-after-free in Mozilla Firefox and Thunderbird allows remote attackers to crash a content process through a WebTransport connection. WebTransportChild retains its WebTransport owner through a raw mTransport pointer, and RecvRemoteClosed calls Cleanup, where promise resolution can dispatch an event that releases the owner before processing completes. Reachability requires remote-close cleanup; affected lines are Firefox before 136, Firefox ESR before 115.21 or 128.8, and Thunderbird before 128.8 or 136.

The record

CVE
CVE-2025-1931
Published
Mar 4, 2025
Updated
Apr 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 2026Record 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
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