CVEvulnerability
CVE-2026-33807
9.1 CRITICAL
Official page ↗
- Status
- Analyzed
- Published
- 2026-04-15
- Last modified
- 2026-10-26
- Assigner
- ce714d77-add3-4f53-aff5-83d477b104bb
- CVSS 3.1 (ce714d77-add3-4f53-aff5-83d477b104bb)
- 9.1 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- Weaknesses
- CWE-436
Description
@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middleware path is prefixed a second time, causing it to never match incoming requests. This results in complete bypass of Express middleware security controls, including authentication, authorization, and rate limiting, for all routes defined within affected child plugin scopes. No special configuration or request crafting is required.
Upgrade to @fastify/express v4.0.5 or later.
Affected configurations
• fastify fastify\/express (< 4.0.5)
Related
Weakness · CWE (1)
- CWE-436 Interpretation Conflict weakness
References
- https://cna.openjsf.org/security-advisories.html Vendor Advisory
- https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c Exploit, Mitigation, Vendor Advisory
- https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c Exploit, Mitigation, Vendor Advisory