A use-after-free vulnerability exists in the content process side of a WebTransport connection in Firefox versions prior to 136 and Firefox ESR versions prior to 115.21 and 128.8. This flaw can lead to a potentially exploitable crash. The vulnerability has been assigned CVE-2025-1931 and is rated high severity with a CVSS score of 7.5. Mozilla has fixed this issue in Firefox 136 and Firefox ESR 115.21 and 128.8.