Vulnerability · Published Jul 23, 2026 · Assigned by VulnCheck

CVE-2025-71389Cal.com before 5.9.9 Remote Code Execution via RSC

Critical 10.0

In plain English

A critical-severity code injection in cal.diy from calcom. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.4% (higher than 72% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 3.1)10.0Critical

Exploit odds (30 days)1.4%top 28.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack tooling1Public PoC

Official 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.

Affected products (as reported)

Vendor	Product	Versions
calcom	cal.diy	0 – before 5.9.9

Weakness: CWE-94 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

References

GitHub Security Advisory (GHSA-qjx2-5xqp-cpf4) vendor-advisory
Patch (PR #25592) issue-tracking, patch
Upstream Next.js advisory (CVE-2025-55182) related
VulnCheck Advisory: Cal.com before 5.9.9 Remote Code Execution via RSC third-party-advisory