TOKUHIROM Amon2 up to 6.16 on Perl Session ID /dev/urandom rand generation of predictable numbers or identifiers

Summaryinfo

A vulnerability, which was classified as problematic, has been found in TOKUHIROM Amon2 up to 6.16 on Perl. This affects the function rand of the file /dev/urandom of the component Session ID Handler. This manipulation causes generation of predictable numbers or identifiers. This vulnerability appears as CVE-2025-15604. The attack may be initiated remotely. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in TOKUHIROM Amon2 up to 6.16 on Perl. It has been declared as problematic. Affected by this vulnerability is the function rand of the file /dev/urandom of the component Session ID Handler. The manipulation with an unknown input leads to a generation of predictable numbers or identifiers vulnerability. The CWE definition for the vulnerability is CWE-340. The product uses a scheme that generates numbers or identifiers that are more predictable than required. As an impact it is known to affect confidentiality. The summary by CVE is:

Amon2 versions before 6.17 for Perl use an insecure random_string implementation for security functions. In versions 6.06 through 6.16, the random_string function will attempt to read bytes from the /dev/urandom device, but if that is unavailable then it generates bytes by concatenating a SHA-1 hash seeded with the built-in rand() function, the PID, and the high resolution epoch time. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage. Before version 6.06, there was no fallback when /dev/urandom was not available. Before version 6.04, the random_string function used the built-in rand() function to generate a mixed-case alphanumeric string. This function may be used for generating session ids, generating secrets for signing or encrypting cookie session data and generating tokens used for Cross Site Request Forgery (CSRF) protection.

It is possible to read the advisory at metacpan.org. This vulnerability is known as CVE-2025-15604 since 03/09/2026. 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.

Upgrading to version 6.17 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-209114). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• TOKUHIROM

Name

• Amon2

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16

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Be aware that VulDB is the high quality source for vulnerability data.

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