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CWE-434: Unrestricted File Upload Vulnerability Exploited

First seen 17 Apr 2026, 17:02 UTC cwe.mitre.org 69

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A critical vulnerability identified as CWE-434 allows unrestricted file uploads of dangerous types, potentially leading to code execution and data compromise. Attackers can exploit this weakness by uploading malicious files to web servers, which may not validate file types correctly. This vulnerability affects various web applications, particularly those using PHP and ASP.NET. The scope of impact includes unauthorized code execution and data manipulation, posing significant risks to affected systems. Security experts emphasize the need for strict input validation and sandboxing measures to mitigate these risks. Current assessments suggest that many organizations remain vulnerable due to inadequate security practices. The situation is urgent as attackers may leverage this weakness for widespread exploitation.

Key Points: • CWE-434 allows attackers to upload dangerous file types, risking code execution. • Inadequate input validation is a primary factor in the vulnerability's exploitation. • Affected systems include those using PHP and ASP.NET, highlighting widespread risk.

Timeline

2026-04-15
CWE-434 vulnerability detailed in cybersecurity article
2026-04-17
Further analysis and recommendations published