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Authorization Bypass in Next.js Middleware

Not in CISA KEVMetasploit moduleCVE-2025-29927CWE-285

Not confirmed exploited. 3 of 8 rule sources name it. Our CRS test: partly blocked.

Edge rules
3/8
Our test
Partly blocked
CVSS
9.1
EPSS
99.2% Top 0.1%
Posts, 14d
02026-10-21: 0 posts2026-10-22: 0 posts2026-10-23: 0 posts2026-10-24: 0 posts2026-10-25: 0 posts2026-10-26: 0 posts2026-10-27: 0 posts2026-10-28: 0 posts2026-10-29: 0 posts2026-10-30: 0 posts2026-10-31: 0 posts2026-11-01: 0 posts2026-11-02: 0 posts2026-11-03: 0 posts
Published
2025-03-21
Next.js is a React framework for building full-stack web applications. Starting in version 1.11.4 and prior to versions 12.3.5, 13.5.9, 14.2.25, and 15.2.3, it is possible to bypass authorization checks within a Next.js application, if the… More

Next.js is a React framework for building full-stack web applications. Starting in version 1.11.4 and prior to versions 12.3.5, 13.5.9, 14.2.25, and 15.2.3, it is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware. If patching to a safe version is infeasible, it is recommend that you prevent external user requests which contain the x-middleware-subrequest header from reaching your Next.js application. This vulnerability is fixed in 12.3.5, 13.5.9, 14.2.25, and 15.2.3.

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Ask about CVE-2025-29927: who's covered, what to patch first, how vendors compare. I cite sources and won't help with attacks.

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Severity, decoded

CVSS 3.1
Critical · 9.1 / 10

Exploitable over the network, with no privileges and no user interaction, leading to full loss of confidentiality and integrity.

Over the internetNo login neededNo user actionWorks reliablySerious impact
How the score is built8 metrics
  • Attack vectorAn attacker can reach it over the internet; no access to your network needed.
    Network
  • Attack complexityNo special conditions are needed; the attack works reliably.
    Low
  • Privileges requiredNo account or login is needed.
    None
  • User interactionNo one has to click or open anything; the attack works on its own.
    None
  • ScopeThe damage stays within the vulnerable component.
    Unchanged
  • Confidentiality impactAn attacker can read all data the affected component holds, or the most sensitive parts of it.
    High
  • Integrity impactAn attacker can change any data or files the affected component protects.
    High
  • Availability impactThe component keeps working normally.
    None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA's assessmentSSVC, from the CVE record
ExploitationNone

CISA has seen no public exploit and no attacks.

AutomatableYes

Attackers can script the attack end to end and hit many targets at once.

Technical impactTotal

A successful attack gives full control over the affected software or all of its data.

Public exploits

3 found
1 Metasploit1 Exploit-DB1 Scanner template0 GitHub PoCs

Links are to third-party code: never run it outside an isolated lab.

Timeline

  1. 2025-03-21
    CVE published
    CVE List
  2. 2025-03-21
    Metasploit module published
    Next.js Middleware Authorization Bypass Scanner
  3. 2025-03-22
    Cloudflare ships a rule
    Next.js - Auth Bypass - CVE:CVE-2025-29927
  4. 2025-03-31
    OWASP CRS ships a rule
    feat: block header related to CVE-2025-29927 (Next.js) (https://github.com/coreruleset/coreruleset/pull/4053)
  5. 2025-04-05
    Exploit published on Exploit-DB
    Next.js Middleware 15.2.2 - Authorization Bypass
  6. 2025-04-28
    F5 ships a rule
    Next.js Middleware Authorization Bypass
  7. 2026-11-02
    Our test: OWASP Core Rule Set blocked part of it
    paranoia level 1, anomaly threshold 5, default CRS settings
  8. 2026-11-02
    Our test: OWASP Core Rule Set blocked part of it
    paranoia level 2, anomaly threshold 5, default CRS settings

Social

2026-10-21: 0 posts2026-10-22: 0 posts2026-10-23: 0 posts2026-10-24: 0 posts2026-10-25: 0 posts2026-10-26: 0 posts2026-10-27: 0 posts2026-10-28: 0 posts2026-10-29: 0 posts2026-10-30: 0 posts2026-10-31: 0 posts2026-11-01: 0 posts2026-11-02: 0 posts2026-11-03: 0 posts

No posts seen yet on X, Bluesky, Mastodon, Hacker News or GitHub.

Vendor statements

Quoted
CloudflareWAF Managed Rules2 quotesRule off by default

First rule 2025-03-22, 1 day after the CVE was published.

2025-03-22New rule…f472013eDefault: DisabledSource
Next.js - Auth Bypass - CVE:CVE-2025-29927. Previous action: N/A. New action: Disabled. This is a New Detection
2025-04-14New rule…d6b2d36cDefault: DisabledSource
Next.js - Auth Bypass - CVE:CVE-2025-29927 - 2. Previous action: Log. New action: Disabled. This is a New Detection
AWSAWS WAF Managed RulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. AWS often describes a vulnerability without naming its CVE (for example "Log4j"). We count only entries that name the CVE, so AWS coverage is understated.

Microsoft AzureFront Door and Application Gateway WAF (DRS)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. The rule tables name CVEs but carry no dates, so Azure is left out of every time-to-rule figure.

Google CloudCloud Armor preconfigured WAF rulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. Google names few CVEs: the release notes start in May 2024 and the rules reference lists CVEs without dates. Its cve-canary rules are opt-in.

FastlyNext-Gen WAF virtual patchesBefore feed history

The CVE predates the oldest entry in this vendor's public feed, so a rule may exist that we cannot see.

F5Attack signatures (Distributed Cloud WAF)1 quoteRule published

First rule 2025-04-28, 38 days after the CVE was published.

2025-04-28New rule200013111Source
Added: signature 200013111 "Next.js Middleware Authorization Bypass" (Authentication/Authorization Attacks, risk High), systems: JavaScript, ReactJS. References: CVE-2025-29927.
AkamaiApp & API Protector (Adaptive Security Engine)No public source

This vendor publishes no machine-readable rule changelog we can check.

OWASP CRSCore Rule Set (open source, used inside many WAFs)1 quoteRule published

First rule 2025-03-31, 10 days after the CVE was published.

2025-03-31New ruleSource
feat: block header related to CVE-2025-29927 (Next.js) (https://github.com/coreruleset/coreruleset/pull/4053)