CVE-2026-6414
@fastify/static versions 8.0.0 through 9.1.0 decode percent-encoded path separators (%2F) before filesystem resolution, while Fastify's router treats them as literal characters. This mismatch allows attackers to bypass route-based middleware or guards that protect files served by @fastify/static. For example, a route guard on a protected path can be circumvented by encoding the path separator in the URL. Upgrade to @fastify/static 9.1.1 to fix this issue. There are no workarounds.
Attack Parameters
Technical Impact
Time Line
Key Metrics
Recommended Solution
Immediate Action Plan
1. Inventory
Identify all affected systems in your infrastructure.
2. Assessment
Assess exposure and criticality for your organization.
3. Mitigation
Apply patches or available workarounds.
4. Verification
Test and confirm effectiveness of applied measures.