Cotonti up to 1.0.0 users.register.php microtime random values

Summaryinfo

A vulnerability classified as problematic has been found in Cotonti up to 1.0.0. Affected by this issue is the function microtime of the file users.register.php. This manipulation causes random values. This vulnerability is tracked as CVE-2026-121553. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in Cotonti up to 1.0.0. It has been declared as problematic. Affected by this vulnerability is the function microtime of the file users.register.php. The manipulation with an unknown input leads to a random values vulnerability. The CWE definition for the vulnerability is CWE-330. The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers. As an impact it is known to affect confidentiality. The summary by CVE is:

Cotonti through 1.0.0 generates registration and email-change validation tokens with md5(microtime()), allowing attackers to bypass email-ownership verification by predicting tokens. Attackers can derive the generation time from the HTTP Date header and compute candidate tokens offline. They then submit these tokens to the users.register.php validate handler to activate accounts or confirm email addresses they do not control.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-121553 since 11/03/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1600.001 according to MITRE ATT&CK.

By approaching the search of inurl:users.register.php it is possible to find vulnerable targets with Google Hacking.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• Cotonti

Version

• 1.0

Website

• Product: https://github.com/Cotonti/Cotonti/

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