Nest Fastify HEAD Request Middleware Bypass

Description

Impact

In a NestJS application using @nestjs/platform-fastify, GET middleware can be bypassed because Fastify automatically redirects HEAD requests to the corresponding GET handlers (if they exist).

As a result:

  • Middleware will be completely skipped.
  • The HTTP response won't include a body (since the response is truncated when redirecting a HEAD request to a GET handler).
  • The actual handler will still be executed.

Patches

Fixed in @nestjs/[email protected]

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2026-03-17 18:38:38 UTC
Updated
2026-03-20 21:21:46 UTC
GitHub reviewed
2026-03-17 18:38:38 UTC
NVD published
2026-03-20

EPSS Score

Score Percentile
0.04% 11.33%

CVSS Scores

Base score Version Severity Vector
8.7 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:H)
High integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.

Identifiers

CWEs

CWE id Name
CWE-670 Always-Incorrect Control Flow Implementation

Credits

  • kamilmysliwiec (remediation_developer)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
npm @nestjs/platform-fastify <= 11.1.15 11.1.16

References

cvelogic Threat Intelligence