CVE-2026-2293 — @nestjs/platform-fastify
Fix: nestjs/nest@fd8d073CVE-2026-2293 is a CWE-863 vulnerability in @nestjs/platform-fastify. A fix is available for @nestjs/platform-fastify — see the affected versions and patch details below.
NestJS 11.1.13 - Lack of data validation allowing authentication/authorization bypass
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-2293.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@nestjs/platform-fastifynpmDescription
Impact
What kind of vulnerability is it? Who is impacted?
A NestJS application using @nestjs/platform-fastify can allow bypass of any middleware when Fastify path-normalization options (e.g., ignoreTrailingSlash, ignoreDuplicateSlashes, useSemicolonDelimiter) are enabled. In affected route-scoped middleware setups, variant paths may skip middleware checks while still reaching the protected handler.
The bug is a path canonicalization mismatch between middleware matching and route matching in Nest’s Fastify adapter.
Nest passes Fastify routerOptions (such as ignoreTrailingSlash, ignoreDuplicateSlashes, useSemicolonDelimiter) to the Fastify router in packages/platform-fastify/adapters/fastify-adapter.ts:253.
But middleware execution is decided by a separate regex check over req.originalUrl in packages/platform-fastify/adapters/fastify-adapter.ts:706 and packages/platform-fastify/adapters/fastify-adapter.ts:713.
If that regex does not match, Nest does next() and skips the middleware (packages/platform-fastify/adapters/fastify-adapter.ts:714), while Fastify may still normalize the same path and route it to the protected handler. So the vulnerability exists because security checks (middleware) and request dispatch(router) use different URL interpretations.
This is a fail-open design issue (inconsistent normalization), not just a bad app config: non-default router options make the mismatch reachable.
Patches
Fixed in @nestjs/[email protected]
References
Credit goes to Fluidattacks (Cristian Vargas) https://fluidattacks.com/advisories/neton
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @nestjs/platform-fastify | all versions | 11.1.14npm install @nestjs/platform-fastify@11.1.14 |
Affected Products
nestnestjsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @nestjs/platform-fastify, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @nestjs/platform-fastify to 11.1.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-2293 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2026-2293 in your dependencies?
Find it across npm, including transitive dependencies.