CVE Tools
Home/Vulnerability/CVE-2026-6270

CVE-2026-6270

@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes

Published: Apr 16, 2026Updated: Apr 16, 2026 Sources: CVE List NVD
NVD MITRE
9.1CVSS
CRITICAL

@fastify/middie versions 9.3.1 and earlier do not register inherited middleware directly on child plugin engine instances. When a Fastify application registers authentication middleware in a parent scope and then registers child plugins with @fastify/middie, the child scope does not inherit the parent middleware. This allows unauthenticated requests to reach routes defined in child plugin scopes, bypassing authentication and authorization checks. Upgrade to @fastify/middie 9.3.2 to fix this issue. There are no workarounds.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None

Weaknesses

CWE-436

Affected Products

@fastify/middie
@fastify/middie

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

References

https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c
github.com
https://github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5w
github.com
https://cna.openjsf.org/security-advisories.html
cna.openjsf.org

Timeline

Published
Apr 16, 2026
Last Updated
Apr 16, 2026

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-6270 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
AI-powered analysis
Plain-language impact assessment and exploitation scenario
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows