This indicates an attack attempt against a security bypass vulnerability in Mozilla Firefox.
The vulnerability is caused by an error when the vulnerable software handles a "for" attribute in a label. It allows a remote attacker to bypass the software's "focus prevention" via sending a crafted web page.
Mozilla Firefox 126.96.36.199, 188.8.131.52 and other versions before 184.108.40.206
SeaMonkey before 1.1.5
Upgrade to the latest version.