Server-Side Request Forgery (SSRF) in Next.js - CVE-2026-64649
Published: July 22, 2026
Vulnerability identifier: #VU139030
CSH Severity: High
CVSS v4: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64649
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause the server to send outbound requests to a malicious host and disclose sensitive information.
The vulnerability exists due to improper input validation in Server Actions when forwarding or redirecting requests using Host-associated headers controlled by the request. A remote attacker can supply crafted Host-associated headers to cause the server to send outbound requests to a malicious host and disclose sensitive information.
Applications are affected when the incoming host header is not fixed to a trusted value.
Affected software
Next.js
How to mitigate CVE-2026-64649
Install security update from vendor's website.
Next.js - addressed in versions 15.5.21, 16.2.11