Firefox vulnerability

It was possible to cause a use-after-free in the content process side of a WebTransport connection, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

Published 4 Mar 2025Updated 5 Oct 20267 sources
CVSS 7.5

What happened

It was possible to cause a use-after-free in the content process side of a WebTransport connection, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

Affected versions

Firefox: before 115.21.0; before 136.0; 116.0 through before 128.8.0; before 128.8.0; 129.0 through before 136.0 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

  • Apply vendor-provided updates or mitigations.
  • Review affected product exposure and access logs.

Public PoC references

No public PoC reference has passed the current publication threshold.