fastify middie up to 9.3.1 interpretation conflict

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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8.0$0-$5k0.00

Summaryinfo

A vulnerability has been found in fastify middie up to 9.3.1 and classified as critical. This impacts an unknown function. Performing a manipulation results in interpretation conflict. This vulnerability is reported as CVE-2026-6270. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in fastify middie up to 9.3.1. It has been classified as critical. This affects an unknown part. The manipulation with an unknown input leads to a interpretation conflict vulnerability. CWE is classifying the issue as CWE-436. Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

@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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-6270 since 04/14/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 9.3.2 eliminates this vulnerability.

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Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.2
VulDB Meta Temp Score: 8.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 9.1
CNA Vector (openjs): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Interpretation conflict
CWE: CWE-436
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: middie 9.3.2

Timelineinfo

04/14/2026 CVE reserved
04/16/2026 +2 days Advisory disclosed
04/16/2026 +0 days VulDB entry created
04/16/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-hrwm-hgmj-7p9c
Status: Confirmed

CVE: CVE-2026-6270 (🔒)
GCVE (CVE): GCVE-0-2026-6270
GCVE (VulDB): GCVE-100-357927

Entryinfo

Created: 04/16/2026 16:47
Changes: 04/16/2026 16:47 (63)
Complete: 🔍
Cache ID: 216::103

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