CVE-2025-71389
Critical
Description
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.
SeverityCritical
CVSS10.0
Exploit probability—
ProductCalcom Cal.diy
PublishedJul 23, 2026
First seenJul 23, 2026
Weakness typeCWE-94Code injection
How to fix
Update
- calcom cal.diy5.9.9 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| calcom cal.diy | v < 5.9.9 | 5.9.9 |
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