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{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,9.3.2)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "9.3.2"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "@fastify/middie", "source": "cna", "vendor": "@fastify/middie"}, "product": "middie", "vendor": "fastify"}], "analysis": {"en": {"generated_at": "2026-04-17T04:05:24.762166+00:00", "value": {"mitigation_remediation": ["Upgrade the @fastify/middie dependency to 9.3.2 or newer.", "If upgrading immediately is not possible, disable the ignoreDuplicateSlashes configuration option so that the router no longer normalises duplicate slashes.", "Audit the application configuration to ensure that the ignoreDuplicateSlashes setting is not enabled in any environment or configuration file."], "summary": {"action": "Immediate Patch", "impact": "Authentication/Authorization Bypass via duplicate slashes"}, "threat_synthesis": {"affected_systems": "The affected component is the @fastify/middie library, versions 9.3.1 and earlier. Applications that include these versions and enable the ignoreDuplicateSlashes configuration option are vulnerable. The issue does not exist in @fastify/middie 9.3.2 or later, nor in applications that do not use the deprecated option.", "description_and_impact": "The vulnerability allows an attacker to bypass middleware authentication and authorization checks by sending requests that contain duplicate slashes, exploiting a mismatch between Fastify\u2019s router normalisation and the middleware path matching logic when the deprecated ignoreDuplicateSlashes option is enabled. This can allow unauthorised access to protected resources or API endpoints.", "risk_and_exploitability": "With a CVSS score of 7.4, the vulnerability is considered high\u2011medium risk. No EPSS data is available, and it is not listed in the CISA known exploited vulnerabilities catalog. The attack vector is local to the web application context and requires an attacker to craft a URL containing duplicate slashes; the patch is only effective when the ignoreDuplicateSlashes option is enabled. If the option is disabled, the vulnerability cannot be exploited."}}}}, "created": "2026-04-16T18:58:29.322090+00:00", "updated": "2026-04-17T04:15:09.338118+00:00", "vendors": ["fastify", "fastify$PRODUCT$middie"]}