The vulnerability in the Security: Process Sandboxing component of Firefox and Thunderbird permits an attacker to disclose sensitive information that should remain confined within the sandbox and to gain elevated privileges inside the browser process. Through these capabilities the attacker can compromise both confidentiality and integrity of data handled by the affected software.

Mozilla Firefox browsers earlier than version 158 and the ESR branch before release 153.5, as well as Mozilla Thunderbird browsers earlier than version 158 and the ESR branch before release 153.5, are vulnerable. All versions of Firefox and Thunderbird that include the patch released in these versions are considered unaffected.

The CVSS score is 8.8, indicating high severity, and the EPSS score is < 1%. Because the vulnerability can lead to privilege escalation, its potential impact remains high. No public exploits are linked, and it is not listed in the CISA Known Exploited Vulnerabilities catalog, but the severity warrants urgent attention until the patch is applied.