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.

References

https://www.vulncheck.com/advisories/cal-com-before-remote-code-execution-via-rsc

https://github.com/calcom/cal.diy/security/advisories/GHSA-qjx2-5xqp-cpf4

https://github.com/calcom/cal.diy/pull/25592

https://github.com/advisories/GHSA-9qr9-h5gf-34mp

Details

Source: Mitre, NVD

Published: 2026-07-23

Updated: 2026-07-23

Risk Information

CVSS v2

Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

Severity: Critical

CVSS v3

Base Score: 10

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Severity: Critical

CVSS v4

Base Score: 10

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Severity: Critical

EPSS

EPSS: 0.00928