An attacker that can control a content process can use the privileged UITour actor to read restricted data or gain elevated privileges within the application. This flaw combines an information exposure weakness with a privilege escalation bug, allowing sensitive information leakage and escalation of control within the browser or mail client.

Mozilla Firefox and Mozilla Thunderbird are affected. Versions up to and including 137 are vulnerable; the issue was fixed in Firefox 138 and Thunderbird 138.

The CVSS score of 7.1 indicates a high severity. The EPSS score is below 1 %, suggesting that exploitation is unlikely at present, and the vulnerability is not listed in CISA’s KEV catalog. The attack path requires an attacker to take control of a content process, which could be achieved through malicious web content or corrupted extensions; this inference is based on the description of content‑process control. No publicly known exploit kits or exploits are reported yet.