{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/vendors/astro/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[{"cvss":8.2,"id":"CVE-2026-59731"}],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["Astro (\u003e= 6.4.7, \u003c 6.4.8)"],"_cs_severities":["high"],"_cs_tags":["authorization-bypass","web-vulnerability","astro","nodejs"],"_cs_type":"advisory","_cs_vendors":["Astro"],"content_html":"\u003cp\u003eA high-severity authorization bypass vulnerability, tracked as CVE-2026-59731, has been identified in Astro web framework versions 6.4.7 and above, specifically affecting versions \u0026gt;= 6.4.7 and \u0026lt; 6.4.8. This issue reintroduces a known middleware authorization bypass pattern stemming from a canonicalization mismatch in URL decoding. Attackers can exploit this by deeply encoding a request path, exceeding the framework's iterative URL decoder's maximum depth of 10. Consequently, Astro's middleware performs authorization decisions on a partially decoded pathname, while subsequent route matching logic applies an additional \u003ccode\u003edecodeURI()\u003c/code\u003e operation, fully resolving the request to a protected route. This discrepancy allows unauthorized access to critical application areas like \u003ccode\u003e/admin\u003c/code\u003e, \u003ccode\u003e/api/admin\u003c/code\u003e, or \u003ccode\u003e/dashboard\u003c/code\u003e, bypassing intended security controls. The vulnerability exists when applications use path-based authorization checks in middleware and pass the request through Astro's rewrite-based routing via \u003ccode\u003enext(context.url)\u003c/code\u003e.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker crafts a deeply URL-encoded request path targeting a protected resource, for example, \u003ccode\u003e/%252525252525252525252561dmin\u003c/code\u003e to bypass \u003ccode\u003e/admin\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe crafted request is sent to the vulnerable Astro application.\u003c/li\u003e\n\u003cli\u003eAstro's \u003ccode\u003eonRequest\u003c/code\u003e middleware intercepts the request, and its iterative URL decoder attempts to process the \u003ccode\u003econtext.url.pathname\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eDue to the excessive encoding depth (11 levels in this example), the decoder reaches its iteration cap (10 iterations) and returns a partially decoded pathname, such as \u003ccode\u003e/%61dmin\u003c/code\u003e, to the middleware.\u003c/li\u003e\n\u003cli\u003eThe middleware performs its authorization check against this partially decoded path. Since \u003ccode\u003e/%61dmin\u003c/code\u003e does not match the protected path \u003ccode\u003e/admin\u003c/code\u003e, the authorization check fails to block the request.\u003c/li\u003e\n\u003cli\u003eThe middleware then invokes \u003ccode\u003enext(context.url)\u003c/code\u003e, forwarding the request to Astro's internal routing logic.\u003c/li\u003e\n\u003cli\u003eAstro's route matching mechanism performs an additional \u003ccode\u003edecodeURI()\u003c/code\u003e operation on the path, fully decoding \u003ccode\u003e/%61dmin\u003c/code\u003e into the canonical \u003ccode\u003e/admin\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe request is then successfully routed to the protected \u003ccode\u003e/admin\u003c/code\u003e endpoint, effectively bypassing the middleware's intended authorization.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-59731 allows an unauthenticated attacker to bypass pathname-based authorization controls in Astro applications. This can lead to unauthorized access to sensitive pages, administrative interfaces, or API endpoints that should otherwise be protected by middleware. Affected applications may expose critical functionalities or data, undermining their security posture. While no specific victim counts or targeted sectors are provided, any Astro application version between 6.4.7 and 6.4.8 that implements path-based middleware authorization is susceptible, potentially impacting a wide range of web services and applications. This vulnerability is a re-occurrence of a previous bypass pattern, indicating a persistent class of issues with URL canonicalization.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003ePatch CVE-2026-59731 immediately:\u003c/strong\u003e Upgrade Astro to a version greater than or equal to 6.4.8 as soon as it is released, or apply the recommended fix from the Astro development team.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eDeploy the Sigma rule:\u003c/strong\u003e Implement the provided Sigma rule to detect attempts at exploiting this authorization bypass by monitoring for deeply URL-encoded paths in webserver logs.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eReview middleware logic:\u003c/strong\u003e Audit existing Astro middleware implementations to identify and rectify any instances where \u003ccode\u003econtext.url.pathname\u003c/code\u003e is used for authorization decisions in conjunction with \u003ccode\u003enext(context.url)\u003c/code\u003e rewrite behavior, ensuring authorization and routing operate on the same canonical pathname representation.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eEnable webserver logging:\u003c/strong\u003e Ensure comprehensive logging of \u003ccode\u003ecs-uri-stem\u003c/code\u003e and \u003ccode\u003ecs-uri-query\u003c/code\u003e in web server logs (e.g., Apache, Nginx, IIS) to facilitate detection of malformed or deeply encoded requests.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-07-20T21:59:25Z","date_published":"2026-07-20T21:59:25Z","id":"https://feed.craftedsignal.io/briefs/2026-07-astro-auth-bypass/","summary":"An authorization bypass vulnerability exists in Astro versions \u003e= 6.4.7 and \u003c 6.4.8, caused by a mismatch in URL path canonicalization, allowing an unauthenticated attacker to bypass middleware protections and access protected routes if the application relies on pathname-based authorization and uses rewrite behavior that performs route matching after middleware execution.","title":"Astro Authorization Bypass via Iterative Decode Limit and Canonicalization Mismatch","url":"https://feed.craftedsignal.io/briefs/2026-07-astro-auth-bypass/"}],"language":"en","title":"CraftedSignal Threat Feed - Astro","version":"https://jsonfeed.org/version/1.1"}