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Vulnerability · Published Jul 27, 2026 · Assigned by GitHub_M

CVE-2026-64649Next.js: Server-Side Request Forgery in Server Actions on Custom Servers

High 8.3

In plain English

A high-severity server-side request forgery in next.js from vercel. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.3High
Exploit odds (30 days)0.5%top 60.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Next.js is a React framework for building full-stack web applications. In versions 14.1.1 through 15.5.20 and 16.0.0 through 16.2.10, when a Server Action forwards or redirects a request, an attacker can cause the server to send that outbound request to a malicious host (Server-Side Request Forgery). This requires the attacker's request to control Host-associated headers. In some configurations, it's also possible to obtain internal values that weaken middleware/proxy authorization. Applications that use Server Actions are affected when the incoming host header is not fixed to a trusted value. This typically occurs on custom servers, or on deployments not behind a proxy that pins the host. Managed hosting pins the host upstream and is not affected; next start and standalone output do the same from version 14.2 onward. This issue has been fixed in versions 15.5.21 and 16.2.11.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npmnext15.5.21GHSA-89xv-2m56-2m9x
npmnext16.2.11GHSA-89xv-2m56-2m9x

Affected products (as reported)

VendorProductVersions
vercel next.js >= 14.1.1, < 15.5.21>= 16.0.0 < 16.2.11

Weakness: CWE-918 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

References