The vulnerability involves improper handling of memory boundaries within Firefox's networking component, causing a use‑after‑free that allows a compromised sandboxed process to escape isolation. The flaw permits an attacker to execute arbitrary code or gain privileges beyond the sandbox, potentially enabling full system compromise if the browser is used. This is a use‑after‑free weakness, known to lead to remote code execution when triggered during normal browsing.

All installations of Mozilla Firefox older than version 158 and Firefox ESR before 153.5 are vulnerable. The defect was addressed in Firefox 158 and ESR 153.5, so only those earlier releases need remediation. The issue impacts users running any of the supported platforms (Windows, macOS, Linux) that host the affected browser versions.

Because the flaw resides in the networking stack, the most direct route to exploitation is through network traffic, such as a malicious HTTP response or embedded content received by the browser. The vulnerability is a remote code‑execution vector with no known public exploit, and its EPSS score is currently unavailable, but the lack of an available exploit does not reduce the inherent severity of a sandbox escape. The lack of KEV listing indicates that no large‑scale attacks have been observed yet, but the high impact warrants prompt mitigation. Attackers could abuse the flaw to breach the sandbox and run arbitrary code, achieving full control of the client machine.