Cal.com (repository calcom/cal.diy) in versions <= 4.7.15 is vulnerable to cross-site scripting (XSS) on the publicly accessible single booking view (e.g., /booking/<id>). Booking question (form field) labels are rendered via React's dangerouslySetInnerHTML without proper input sanitization or CSP, so an attacker who can create an event type with a malicious booking question label can inject arbitrary HTML/JavaScript that executes when a victim visits the booking view URL. Self-hosted instances with open registration are particularly at risk.
The issue is fixed in version 4.7.16.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
Low
Basic privileges needed
User Interaction
Passive
Minimal interaction
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
Low
Partial disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 3
https://github.com/calcom/cal.diy/commit/00689fda0a30b8f933c096f02c1fe092a4206d…
disclosure@vulncheck.com
https://github.com/calcom/cal.diy/security/advisories/GHSA-vgj7-76cw-h6f8
disclosure@vulncheck.com
https://www.vulncheck.com/advisories/cal-com-through-cross-site-scripting-via-b…
disclosure@vulncheck.com