Arc before 2024-08-26 allows remote code execution in JavaScript boosts. Boosts that run JavaScript cannot be shared by default; however (because of misconfigured Firebase ACLs), it is possible to create or update a boost using another user's ID. This installs the boost in the victim's browser and runs arbitrary Javascript on that browser in a privileged context. NOTE: this is a no-action cloud vulnerability with zero affected users.
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
1.2% chance of exploitation in the next 30 days; higher than 69% of CVEs (scores of 2026-10-31)