# CVE-2025-29927: Authorization Bypass in Next.js Middleware

- Exploited (CISA KEV): no
- Published: 2025-03-21
- CVSS: 9.1 CRITICAL (v3.1)
- EPSS: 99.2% (100th percentile)
- CWE: CWE-285

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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Rule off by default | 2025-03-22 | 1 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2025-04-28 | 38 |
| Akamai | No public source | — | — |
| OWASP CRS | Rule published | 2025-03-31 | 10 |

### Cloudflare

- 2025-03-22 · new · rule 34583778093748cc83ff7b38f472013e · default Disabled
  > Next.js - Auth Bypass - CVE:CVE-2025-29927. Previous action: N/A. New action: Disabled. This is a New Detection
  Source: https://developers.cloudflare.com/changelog/post/2025-03-22-emergency-waf-release/
- 2025-04-14 · new · rule 9209bb65527f4c088bca5ffad6b2d36c · default Disabled
  > Next.js - Auth Bypass - CVE:CVE-2025-29927 - 2. Previous action: Log. New action: Disabled. This is a New Detection
  Source: https://developers.cloudflare.com/changelog/post/2025-04-14-waf-release/

### F5

- 2025-04-28 · new · rule 200013111
  > Added: signature 200013111 "Next.js Middleware Authorization Bypass" (Authentication/Authorization Attacks, risk High), systems: JavaScript, ReactJS. References: CVE-2025-29927.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2025-05-22 · new · rule 200013111
  > Added: signature 200013111 "Next.js Middleware Authorization Bypass" (Authentication/Authorization Attacks, risk High), systems: JavaScript, ReactJS. References: CVE-2025-29927.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

### OWASP CRS

- 2025-03-31 · new
  > feat: block header related to CVE-2025-29927 (Next.js) (https://github.com/coreruleset/coreruleset/pull/4053)
  Source: https://github.com/coreruleset/coreruleset/blob/main/CHANGES.md

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: partial (2 of 5 requests blocked), template CVE-2025-29927, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: partial (2 of 5 requests blocked), template CVE-2025-29927, 2026-11-02

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2025-29927 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2025-29927