@fastify/jwt is a JSON Web Token plugin for Fastify. In versions before 10.2.2, a per-request verification key passed to request.jwtVerify({ key }) is silently overridden by the plugin's globally configured secret, because the option merge applies the global key last. Applications that use different keys for different authorization domains, for example separate user and admin keys, therefore accept a token signed with the global key on a route that explicitly requires another key. This lets an ordinary authenticated user cross a key-based trust boundary without knowing either secret. The issue is fixed in @fastify/jwt 10.2.2, where an explicit per-call key takes precedence over the global secret. Users should upgrade to 10.2.2.

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Sat, 15 Aug 2026 13:30:00 +0000

Type Values Removed Values Added
Description @fastify/jwt is a JSON Web Token plugin for Fastify. In versions before 10.2.2, a per-request verification key passed to request.jwtVerify({ key }) is silently overridden by the plugin's globally configured secret, because the option merge applies the global key last. Applications that use different keys for different authorization domains, for example separate user and admin keys, therefore accept a token signed with the global key on a route that explicitly requires another key. This lets an ordinary authenticated user cross a key-based trust boundary without knowing either secret. The issue is fixed in @fastify/jwt 10.2.2, where an explicit per-call key takes precedence over the global secret. Users should upgrade to 10.2.2.
Title @fastify/jwt vulnerable to authorization bypass via global secret overriding the per-request key
Weaknesses CWE-347
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-08-15T13:16:12.473Z

Reserved: 2026-07-31T16:13:54.374Z

Link: CVE-2026-18500

cve-icon Vulnrichment

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cve-icon NVD

Status : Received

Published: 2026-08-15T14:17:07.473

Modified: 2026-08-15T14:17:07.473

Link: CVE-2026-18500

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses