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HIGH

CVE-2026-84469

CVSS v3

7.5

HIGH

EPSS Score

0.5 %

exploit probability, as of 2026-09-29

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

fastify versions before 5.12.2 decide whether to compile a request schema based on JavaScript truthiness, but JSON Schema Draft 7 defines the boolean false as a valid schema that rejects every instance. When an application assigns false to a route's body, querystring, params, or headers schema to deny all input, fastify treats it as a missing schema, compiles no validator, and runs the route handler on any request. An unauthenticated remote client can therefore reach a handler that a valid deny-

Technical details

Published
2026-09-04
Last Modified
2026-09-04

Frequently asked questions

What is CVE-2026-84469?

fastify versions before 5.12.2 decide whether to compile a request schema based on JavaScript truthiness, but JSON Schema Draft 7 defines the boolean false as a valid schema that rejects every instance. When an application assigns false to a route's body, querystring, params, or headers schema to deny all input, fastify treats it as a missing schema, compiles no validator, and runs the route handler on any request. An unauthenticated remote client can therefore reach a handler that a valid deny-

Is CVE-2026-84469 actively exploited?

Active exploitation of CVE-2026-84469 has not been confirmed. Its EPSS score was 0.5% on 2026-09-29, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-84469?

CVE-2026-84469 has a CVSS v3 base score of 7.5 (HIGH severity).

Is CVE-2026-84469 affecting your environment?

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