{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/products/middie/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[{"cvss":9.1,"id":"CVE-2026-6270"}],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["middie"],"_cs_severities":["critical"],"_cs_tags":["fastify","middlie","authentication bypass","cve-2026-6270"],"_cs_type":"advisory","_cs_vendors":["Fastify"],"content_html":"\u003cp\u003eFastify is a fast and low overhead web framework for Node.js. @fastify/middie is a middleware engine for Fastify. A critical vulnerability, CVE-2026-6270, exists in @fastify/middie versions 9.3.1 and earlier. This flaw stems from the failure to register inherited middleware directly on child plugin engine instances. Specifically, when authentication middleware is established in a parent scope of a Fastify application, any subsequent child plugins utilizing @fastify/middie will fail to inherit this middleware. Consequently, routes defined within these child plugin scopes become susceptible to unauthenticated requests, effectively bypassing intended authentication and authorization mechanisms. The recommended remediation is to upgrade to @fastify/middie version 9.3.2, which addresses this vulnerability.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker identifies a Fastify application using @fastify/middie versions 9.3.1 or earlier.\u003c/li\u003e\n\u003cli\u003eThe application has authentication middleware registered in a parent scope to protect certain routes.\u003c/li\u003e\n\u003cli\u003eThe attacker discovers a child plugin registered with @fastify/middie, which is intended to inherit the parent's authentication middleware.\u003c/li\u003e\n\u003cli\u003eDue to the vulnerability, the child plugin does not properly inherit the authentication middleware.\u003c/li\u003e\n\u003cli\u003eThe attacker crafts a request to a route within the vulnerable child plugin.\u003c/li\u003e\n\u003cli\u003eThe request bypasses the authentication checks that were intended to protect the route.\u003c/li\u003e\n\u003cli\u003eThe server processes the unauthenticated request and potentially exposes sensitive data or functionality.\u003c/li\u003e\n\u003cli\u003eThe attacker successfully accesses protected resources without proper authorization, potentially leading to data breaches or unauthorized actions.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-6270 allows attackers to bypass authentication mechanisms in Fastify applications using vulnerable versions of @fastify/middie. This can lead to unauthorized access to sensitive data, modification of application settings, or execution of privileged actions. The CVSS v3.1 base score for this vulnerability is 9.1, indicating a critical severity level. Organizations using affected versions of @fastify/middie are at risk of data breaches, compliance violations, and reputational damage if this vulnerability is exploited.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eImmediately upgrade to @fastify/middie version 9.3.2 to remediate CVE-2026-6270 (reference: Overview section).\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule to identify potential exploitation attempts targeting vulnerable Fastify applications (reference: rule \u0026quot;Detect Unauthenticated Access to Fastify Child Routes\u0026quot;).\u003c/li\u003e\n\u003cli\u003eReview Fastify application configurations to identify instances where authentication middleware is intended to be inherited by child plugins using @fastify/middie (reference: Overview section).\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-09T12:00:00Z","date_published":"2024-01-09T12:00:00Z","id":"https://feed.craftedsignal.io/briefs/2024-01-fastify-middlie-bypass/","summary":"Fastify middlie versions 9.3.1 and earlier do not properly register inherited middleware, leading to authentication bypass in child plugin scopes, allowing unauthenticated access.","title":"Fastify Middlie Authentication Bypass Vulnerability (CVE-2026-6270)","url":"https://feed.craftedsignal.io/briefs/2024-01-fastify-middlie-bypass/"}],"language":"en","title":"CraftedSignal Threat Feed - Middie","version":"https://jsonfeed.org/version/1.1"}