CVE-2025-71389

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.

Affected products

Cal.Com, Next.Js

Fix

Available

CVSS 4.0

10.0 CRITICAL

CVSS 3.1

10.0 CRITICAL

EPSS

1.2% (66th percentile)

Weakness

CWE-94

NVD status

Deferred

Published

2026-07-23