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Next.jsApplication · Vercel

CVE-2026-64649

MEDIUM · 6.5 CVSS v3.1 Developing Published 2026-07-27
Fix available
A fix is available. Upgrade to 15.5.21 / 16.2.11 or later.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click 3 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 6d ago

Surfaced from public web coverage — external links open in a new tab.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · low confidence
Developing — this CVE was published recently and its authoritative NVD entry is still being established, so we're holding a technical summary until the source data settles rather than publish something unreliable. Re-checking after 2026-08-10.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Next.jsApplication
Affected:>= 14.1.1, < 15.5.21>= 16.0.0, < 16.2.11

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 15.5.21 / 16.2.11 or later
Fixed in 15.5.2116.2.11
Recommended fix High confidence

Next.js 15.5.21 or 16.2.11 (depending on your major version branch)

  1. Identify your current Next.js version by checking package.json or running npm list next
  2. If using Next.js 15.x (versions 15.5.20 and below), upgrade to version 15.5.21 or later
  3. If using Next.js 16.x (versions 16.2.10 and below), upgrade to version 16.2.11 or later
  4. Run npm install or yarn to update dependencies
  5. Test that Server Actions continue to function correctly after upgrade
  6. If using a custom server, verify that host header validation is working as expected
  7. Ensure any internal or secret values are no longer exposed through host header manipulation
Caveat Review Next.js release notes for 15.5.21 and 16.2.11 for any breaking changes; minor version upgrades typically have low risk but test thoroughly

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $2,850. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-64649 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data