OwnCloud Guests - Information Disclosure (CVE-2025-59716)
Description
OwnCloud Guests before 0.12.5 allows unauthenticated user enumeration via the /apps/guests/register/{email}/{token} endpoint. Because of insufficient validation of the supplied token in showPasswordForm, the server responds differently when an e-mail address corresponds to a valid pending guest user rather than a non-existent user.
psychologyCrowdSec Analysis
CVE-2025-59716 is an information disclosure vulnerability in ownCloud Guests before version 0.12.5 that allows unauthenticated attackers to enumerate valid guest user email addresses via the /apps/guests/register/{email}/{token} endpoint. By exploiting insufficient token validation, attackers can determine whether a specific email address is registered as a pending guest, potentially aiding in targeted phishing or social engineering attacks.
CrowdSec has been tracking this vulnerability and its exploits since 1st of April 2026.
Insights from the CrowdSec network reveal that the attackers trying to exploit CVE-2025-59716 are composed of a fairly even mix of opportunistic and targeted actors. Some attackers employ preliminary reconnaissance, while others use indiscriminate scanning. CrowdSec data also reveals a clear uptick in attacks involving CVE-2025-59716 over the past week. Activity is above the usual baseline, suggesting growing attention from attackers. This may reflect rising awareness, recent exploit releases, or expanded targeting efforts.
Attackers exploit the endpoint /apps/guests/register/{email}/{token} to enumerate valid guest users in ownCloud by observing responses to crafted requests with arbitrary email addresses and invalid tokens. This allows unauthenticated probing for existing guest accounts.
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| Event | Date |
|---|---|
| CVE Published | 2025-11-05 |
| Rule Released | 2026-04-01 |
| CrowdSec First Seen | 2026-04-01 |
Related Weaknesses
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.