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CVE-2023-36899 is an ASP.NET Framework elevation of privilege vulnerability involving the legacy cookieless session mechanism and its interaction with IIS path handling. The vulnerable behavior arises from ASP.NET cookieless URL rewriting, where session identifiers embedded in URL path segments can be processed in a way that alters the effective path seen by the application after IIS path-based protections have been applied. Research associated with this CVE describes repeated abuse of cookieless path segments to trigger incorrect path normalization and rewriting, including behavior attributed to RemoveAppPathModifier as used by RemoveCookielessValuesFromPath in CookielessHelperClass. This can enable bypass of IIS restricted-path protections, including authentication and path-based filtering, and can also cause application pool confusion in which a request is executed under a parent application's application pool rather than the intended child application's pool. Microsoft classified the issue as an ASP.NET elevation of privilege vulnerability and addressed the original issues in the August 2023 security updates.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos (1 hidden).
This repository contains a single C++ proof-of-concept exploit (PoC.cpp) targeting web applications that use cookieless session tokens in URL paths, a pattern commonly seen in ASP.NET applications. The exploit crafts a malicious URL by inserting repeated cookieless session tokens (e.g., (S(X))) into the path, potentially bypassing access controls or triggering unintended behavior in the web application's routing logic. The code uses the WinHTTP library to send a GET request to the crafted URL and prints the server's response, allowing the user to observe the result of the exploit attempt. The repository is structured as a single file, with all logic contained in the main function, and is intended to demonstrate the exploitability of this specific path manipulation vulnerability.
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8 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A specific vulnerability listed as suspected to be exploited by Iran-linked actors in real-world campaigns; no further technical detail is provided in the content.
Referenced only as part of a related/next article title about IIS auth bypass and app pool privilege escalation in ASP.NET Framework; no substantive discussion is provided in the content.
An ASP.NET/.NET Framework cookieless path handling flaw that can enable IIS restricted path bypass, authentication/path-filter bypass, and application pool confusion that may lead to privilege escalation.
Referenced by title only as part of 'Cookieless DuoDrop', described as an IIS authentication bypass issue in ASP.NET Framework.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.