CVE-2019-25337 in OwnCloud
Summary
by MITRE • 02/13/2026
OwnCloud 8.1.8 contains a username enumeration vulnerability that allows remote attackers to discover user accounts by manipulating the share.php endpoint. Attackers can send crafted GET requests to /index.php/core/ajax/share.php with a wildcard search parameter to retrieve comprehensive user information.
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Analysis
by VulDB Data Team • 02/13/2026
The vulnerability identified as CVE-2019-25337 represents a critical username enumeration flaw within OwnCloud version 8.1.8 that exposes user account information through improper input validation in the share.php endpoint. This weakness allows remote attackers to systematically identify valid user accounts by exploiting the application's response behavior when processing search queries, effectively creating a reconnaissance mechanism that undermines the security posture of the file sharing platform. The vulnerability specifically manifests when the application processes wildcard search parameters through the core ajax share functionality, enabling attackers to enumerate user accounts without authentication credentials.
The technical implementation of this vulnerability stems from inadequate input sanitization and response handling within the share.php endpoint. When attackers submit crafted GET requests containing wildcard characters to the /index.php/core/ajax/share.php resource, the application fails to properly validate the search parameters and instead returns detailed user information in its responses. This behavior violates fundamental security principles by providing attackers with actionable intelligence about valid user accounts, including usernames and potentially associated metadata, which can be leveraged for subsequent attacks such as credential stuffing, targeted phishing campaigns, or brute force attempts against discovered accounts.
The operational impact of this vulnerability extends beyond simple information disclosure, creating a significant risk vector for attackers seeking to compromise the OwnCloud environment. The enumeration capability enables adversaries to build comprehensive user account databases that can be used for various malicious activities including social engineering attacks, targeted credential compromise attempts, and privilege escalation within the system. According to CWE-200, this vulnerability falls under information disclosure categories, while its exploitation aligns with ATT&CK technique T1087.001 for account discovery and T1566 for social engineering attacks. The vulnerability essentially provides attackers with a systematic approach to user account reconnaissance that bypasses traditional authentication mechanisms.
Organizations utilizing affected OwnCloud versions face substantial security risks from this enumeration vulnerability, particularly in environments where user account information could be leveraged for broader attacks. The vulnerability's remote exploitability means that attackers can perform enumeration from any network location without requiring local system access or prior authentication, making it particularly dangerous for organizations with public-facing file sharing services. Mitigation strategies should include immediate patching to version 8.2.2 or later where this vulnerability has been addressed, implementing rate limiting on share endpoint access, and configuring proper input validation to reject malformed search parameters. Additionally, network-level controls such as firewall rules and intrusion detection systems can help monitor and restrict access patterns that indicate enumeration attempts. The vulnerability highlights the importance of proper input validation and secure error handling practices as outlined in OWASP Top Ten categories and demonstrates how seemingly minor implementation flaws can create significant security weaknesses in authentication and access control systems.