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CVE-2026-13181 is an unsafe type-resolution vulnerability in the RadAsyncUpload component of Progress Telerik UI for ASP.NET AJAX prior to version 2026.2.708. Forged upload metadata can control the AsyncUploadTypeName value, allowing resolution of an attacker-specified .NET type without an adequate allowlist. Where a server-side FileUploaded handler accesses UploadResult, manipulated metadata is deserialized into the selected type. This can be combined with a deserialization gadget such as System.Configuration.Install.AssemblyInstaller to cause loading of an attacker-supplied managed or mixed-mode assembly.
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2 valid exploits after Mallory filtered fakes, detection scripts, and README-only repos.
This 62-file repository is an operational, lab-oriented Telerik/IIS exploitation suite rather than a framework module. Its main Python entry points are exploit/telerik_rce.py, telerik_exploit.py, and the Chain 2/3 variants; tools/ contains alternate upload, crypto-forging, padding-oracle, and full-chain drivers. The primary implemented path detects Telerik.Web.UI.WebResource.axd?type=rau, creates or loads forged rauPostData, uploads an ASPX webshell or marker DLL into a selected writable path (including C:\inetpub\wwwroot), attempts to finalize Telerik's .tmp upload, and accesses the resulting shell to run cmd.exe commands as the IIS app-pool identity. Supporting ASPX/C#/C++ files build a deliberately vulnerable Windows IIS lab, introspect Telerik internals through reflection, generate valid encrypted state, and provide benign marker payloads. The repository also claims alternate RadPersistenceManager cookie/path-traversal and RadDockLayout/ViewState-deserialization routes plus AES-CBC padding/timing-oracle key defeat. However, its own VERDICT states the demonstrated result was the known-key RadAsyncUpload upload-to-webroot webshell path; the oracle and alternate deserialization chains were not validated, and its documented AssemblyInstaller setter path alone does not load a standard managed assembly. No external C2 endpoint is embedded; networking is directed at an operator-supplied target URL or localhost lab endpoints.
This 35-file repository is a functional standalone Go exploit and Windows payload suite for a claimed Telerik UI for ASP.NET AJAX RadAsyncUpload padding-oracle-to-RCE chain. It is not a Metasploit, Nuclei, or other recognized exploit-framework module. The primary executable is telerik-rau-exploit/main.go, supported by Go components for HTTP I/O, handler and postback oracle vectors, AES-CBC/PBKDF2 crypto, ciphertext forgery, temp-folder recovery, upload processing, trigger phases, checkpointing, and extensive offline/mock-server tests. Dockerfile and docker-compose support containerized execution of the Go client. The exploit extracts valid _serializedConfiguration and _serializedConfigurationType values from a RadAsyncUpload page, identifies the AllowedFileExtensions location, and uses distinguishable Telerik error responses as an AES-CBC PKCS#7 padding oracle. It forges configuration and MetaData tokens, permits DLL uploads, and uses the System.Configuration.Install.AssemblyInstaller deserialization gadget to call Assembly.LoadFrom on an uploaded mixed-mode DLL. It supports direct AES forgery if the Telerik configuration encryption key is known, handler-oracle and postback-oracle modes, optional TempTargetFolder injection/traversal, resumable JSON state, and a vulnerability-check-only mode. The advertised timing oracle is explicitly a nonfunctional placeholder. The ijw-dll-payload subtree contains C++/CLI source and PowerShell build scripts for x64 and x86 IJW DLLs plus a C# ASPX shell stub. In write mode, DllMain identifies the IIS physical web root from w3wp.exe's per-pool configuration and writes a self-decrypting ASPX shell. In memory mode, DllMain starts a native thread that uses .NET reflection to register/patch an IHttpModule into ASP.NET application instances, providing command execution without writing a webshell to disk. Payload configuration blocks, shell filenames, command header names, assembly names, embedded shell bytes, and optional logging paths are patched before upload.
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10 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A high-severity unguarded .NET type-resolution/deserialization flaw in Telerik UI for ASP.NET AJAX RadAsyncUpload. When chained with the encryption flaws, it enables unauthenticated remote code execution as the IIS application-pool identity.
An unsafe type-resolution and deserialization issue in Telerik RadAsyncUpload upload metadata. In the described chain, a FileUploaded handler reading UploadResult can deserialize attacker-controlled data into a chosen type; use of the System.Configuration.Install.AssemblyInstaller gadget enables loading an uploaded mixed-mode DLL and native-code execution through DllMain.
An unsafe .NET type-resolution and deserialization issue in Telerik RadAsyncUpload upload metadata. Combined with the padding-oracle flaw, it can load an uploaded mixed-mode DLL and achieve remote native-code execution in the IIS worker process.
A remote code execution vulnerability in Progress Telerik UI for ASP.NET AJAX caused by forged upload metadata influencing AsyncUploadTypeName processing and unsafe attacker-controlled type resolution.
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