Cal.com (calcom/cal.diy) before 5.9.9 is vulnerable to unauthenticated remote code execution because it bundles a version of Next.js whose React Server Components (RSC) request handling deserializes attacker-controlled input. A remote attacker can send a crafted RSC request to the server and cause arbitrary code to be executed during server-side processing, without authentication or user interaction. The flaw derives from the upstream Next.js vulnerability CVE-2025-55182 and is resolved in 5.9.9 by updating the affected dependency.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
References 4
https://github.com/advisories/GHSA-9qr9-h5gf-34mp
disclosure@vulncheck.com
https://github.com/calcom/cal.diy/pull/25592
disclosure@vulncheck.com
https://github.com/calcom/cal.diy/security/advisories/GHSA-qjx2-5xqp-cpf4
disclosure@vulncheck.com
https://www.vulncheck.com/advisories/cal-com-before-remote-code-execution-via-r…
disclosure@vulncheck.com