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Medium severity6.5OSV Advisory· Published Jul 27, 2026· Updated Jul 29, 2026

CVE-2026-64649

CVE-2026-64649

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

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
nextnpm
>= 14.1.1, < 15.5.2115.5.21
nextnpm
>= 16.0.0, < 16.2.1116.2.11

Affected products

17

Patches

Vulnerability mechanics

References

6

News mentions

4