Dancer2 up to 2.1.0 Session Factory SessionFactory.pm generate_id random values

Summaryinfo

A vulnerability labeled as problematic has been found in Dancer2 up to 2.1.0. This affects the function generate_id of the file lib/Dancer2/Core/Role/SessionFactory.pm of the component Session Factory. Such manipulation leads to random values. This vulnerability is listed as CVE-2026-13577. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Dancer2 up to 2.1.0. Affected by this issue is the function generate_id of the file lib/Dancer2/Core/Role/SessionFactory.pm of the component Session Factory. The manipulation with an unknown input leads to a random values vulnerability. Using CWE to declare the problem leads to CWE-330. The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers. Impacted is confidentiality. CVE summarizes:

Dancer2 versions through 2.1.0 for Perl generate insecure session ids when CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id when both Math::Random::ISAAC::XS and Crypt::URandom are unavailable. The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function). These are all low-entropy and easily guessed sources. The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications. Predictable session ids could allow an attacker to gain access to systems.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-13577 since 06/28/2026. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1600.001 by the MITRE ATT&CK project.

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

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Productinfo

Name

• Dancer2

Version

• 2.0
• 2.1.0

CPE 2.3info

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CPE 2.2info

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