Vulnerability Description
Dancer2 versions through 2.1.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id unless both Math::Random::ISAAC::XS and Crypt::URandom are available. 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/PerlDancer/Dancer2/blob/v2.1.0/lib/Dancer2/Core/Role/SessionF
- https://www.cve.org/CVERecord?id=CVE-2026-5080
FAQ
What is CVE-2026-13577?
CVE-2026-13577 is a vulnerability with a CVSS score of 8.2 (HIGH). Dancer2 versions through 2.1.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in ...
How severe is CVE-2026-13577?
CVE-2026-13577 has been rated HIGH with a CVSS base score of 8.2/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-13577?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.