CVE-2026-22031
8.4 · HIGHOverview
CVE-2026-22031 is a high-severity vulnerability affecting fastify fastify\/middie. It was published on January 19, 2026 and has a CVSS 3.1 base score of 8.4 (HIGH).
This vulnerability has a CVSS 3.1 base score of 8.4, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical Description
@fastify/middie is the plugin that adds middleware support on steroids to Fastify. A security vulnerability exists in @fastify/middie prior to version 9.1.0 where middleware registered with a specific path prefix can be bypassed using URL-encoded characters (e.g., `/%61dmin` instead of `/admin`). While the middleware engine fails to match the encoded path and skips execution, the underlying Fastify router correctly decodes the path and matches the route handler, allowing attackers to access protected endpoints without the middleware constraints. Version 9.1.0 fixes the issue.
Remediation
Check the references section for vendor advisories and patches from fastify. Update fastify\/middie to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| fastify | fastify\/middie | >= 0, < 9.1.0 | Affected |
Frequently Asked Questions
What is CVE-2026-22031?
CVE-2026-22031 is a high-severity vulnerability affecting fastify fastify\/middie. It was published on January 19, 2026 and has a CVSS 3.1 base score of 8.4 (HIGH).
How severe is CVE-2026-22031?
This vulnerability has a CVSS 3.1 base score of 8.4, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2026-22031?
Check the references section for vendor advisories and patches from fastify. Update fastify\/middie to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-22031?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-22031 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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