Use‑after‑free in the Crash Reporting component has been identified. The flaw allows a reference to a deallocated object to be accessed, leading to memory corruption. This vulnerability was fixed in Firefox 158 and ESR 153.5, as well as Thunderbird 158 and ESR 153.5.

All Mozilla Firefox releases prior to version 158, Firefox ESR versions older than 153.5, Thunderbird releases prior to 158, and Thunderbird ESR versions older than 153.5 are vulnerable. The issue was addressed in Firefox 158, ESR 153.5, Thunderbird 158, and ESR 153.5. Users running earlier builds of Firefox, ESR, or Thunderbird are potentially exposed.

The CVSS score for this vulnerability is 5.4, indicating moderate severity. The EPSS score of 0.00217 (0.217%) suggests a very low probability of exploitation. It is not listed in the CISA KEV catalog. The flaw is a use‑after‑free in the Crash Reporting component, allowing access to a deallocated object that can corrupt memory. Based on the description, the likely attack vector involves a malicious web page or local content that triggers crash reporting, potentially leading to denial of service or remote code execution, though no public exploitation evidence is available.