CVE-2025-27602 in Umbraco
Summary
by MITRE • 03/11/2025
Umbraco is a free and open source .NET content management system. In versions of Umbraco's web backoffice program prior to versions 10.8.9 and 13.7.1, via manipulation of backoffice API URLs, it's possible for authenticated backoffice users to retrieve or delete content or media held within folders the editor does not have access to. The issue is patched in versions 10.8.9 and 13.7.1. No known workarounds are available.
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Analysis
by VulDB Data Team • 09/22/2025
The vulnerability identified as CVE-2025-27602 affects Umbraco content management systems where unauthorized access to content and media resources can occur through manipulation of backoffice API endpoints. This security flaw specifically impacts versions prior to 10.8.9 and 13.7.1, representing a critical authorization bypass issue that undermines the fundamental security model of the CMS. The vulnerability stems from insufficient access control validation within the backoffice API layer, allowing authenticated users to exploit URL manipulation techniques to access restricted resources.
The technical implementation of this vulnerability resides in the improper validation of user permissions when processing API requests within Umbraco's administrative interface. When authenticated backoffice users manipulate API URLs to target specific content or media folders, the system fails to adequately verify whether the requesting user possesses the necessary permissions to access the targeted resources. This represents a classic authorization bypass vulnerability classified under CWE-285, which specifically addresses insufficient authorization checks in software systems. The flaw operates at the application logic level where access control decisions are made, rather than at the network or infrastructure layer, making it particularly challenging to detect and mitigate.
The operational impact of this vulnerability extends beyond simple unauthorized data access, as it enables authenticated attackers to perform both read and delete operations on content and media assets they should not be permitted to access. This creates significant risks for organizations relying on Umbraco for content management, as malicious insiders or compromised legitimate accounts could exploit this weakness to exfiltrate sensitive information, delete critical content, or disrupt content delivery operations. The vulnerability affects the core integrity and availability of the CMS, potentially leading to data loss, content manipulation, and service disruption that could impact business operations and customer experience. According to ATT&CK framework, this vulnerability maps to T1078.004 (Valid Accounts: Cloud Accounts) and T1566.002 (Phishing: Spearphishing Attachments) as it can be exploited by both compromised legitimate users and through social engineering to gain unauthorized access.
Organizations must immediately implement the patched versions 10.8.9 and 13.7.1 to remediate this vulnerability, as no known workarounds exist that would maintain full functionality while addressing the authorization bypass issue. The patch addresses the root cause by implementing proper access control validation mechanisms within the backoffice API endpoints, ensuring that all resource access requests are properly authenticated and authorized before any content or media operations are permitted. Security teams should conduct comprehensive audits of their Umbraco installations to verify all systems have been updated and monitor for any suspicious access patterns that might indicate exploitation attempts. Additionally, organizations should review their access control policies and implement least privilege principles to minimize potential impact should similar vulnerabilities be discovered in the future.