CVE-2025-59716 Scanner

ownCloud Guests is a feature used in collaboration environments, allowing external users to be invited to collaborate without needing a full user account. Businesses and organizations integrate this functionality into their systems to facilitate easy collaboration with clients or external partners. The software is generally deployed alongside other ownCloud services to help consolidate user management and enhance productivity. It is widely utilized by entities seeking secure and manageable ways to extend their network to include guest users. This extension supports the main ownCloud platform by simplifying access for individuals not part of the core organization. Such integrations are vital for seamless communications and project management across different workstreams.

The detected vulnerability allows unauthorized attackers to enumerate valid guest users by exploiting the insufficient validation of the token in the showPasswordForm endpoint. Such vulnerabilities could potentially facilitate further targeted attacks by providing attackers with information about existing user accounts. User enumeration is a critical vulnerability as it can form the basis of more sophisticated attacks, such as brute-forcing credentials or social engineering. It highlights the importance of robust token validation mechanisms in protecting user accounts from unauthorized disclosures. Companies must be vigilant in ensuring their software compliance with security best practices to guard against these risks. The CVE-2025-59716 outlines the specifics of this vulnerability related to ownCloud Guests.

The vulnerability resides in the /apps/guests/register/{email}/{token} endpoint of ownCloud Guests before version 0.12.5. Attackers can trigger the issue without any authentication requirements, making it particularly noteworthy. The issue stems from the inadequate verification of tokens during the password form display process. By manipulating the token parameter, an attacker can receive responses indicating whether an email corresponds to a valid guest user. This flaw can be consistently exploited to gather data on user registrations within the system. As this problem impacts versions before 0.12.5, it underscores the need for prompt upgrades and patch implementations.

If exploited, this user enumeration vulnerability can lead to privacy breaches where attacker insights into registered guest users pave the way for subsequent attacks. Such attacks may involve phishing, brute-forcing passwords, or other malicious exploits targeted at identified users. This exposure impacts organizational security by revealing potential doors for attackers to escalate their activities. Continuous exposure to this vulnerability could weaken user trust and undermine the confidentiality of communications and collaborations. The presence of unauthorized guests also risks the integrity and availability of shared resources within an organization. Precautionary updates are necessary to mitigate these risks and maintain a secure user environment.

REFERENCES

• https://nvd.nist.gov/vuln/detail/CVE-2025-59716
• https://gist.github.com/thesmartshadow/64ae0449e909174d0479a4f23657147f
• https://marketplace.owncloud.com/apps/guests