======================================================================== CVE-2026-13577 CPAN Security Group ======================================================================== CVE ID: CVE-2026-13577 Distribution: Dancer2 Versions: through 2.1.0 MetaCPAN: https://metacpan.org/dist/Dancer2 VCS Repo: https://github.com/PerlDancer/Dancer2 Dancer2 versions through 2.1.0 for Perl generate insecure session ids when CSPRNG modules are unavailable Description ----------- 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. Problem types ------------- - CWE-340 Generation of Predictable Numbers or Identifiers - CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator Workarounds ----------- Ensure Crypt::URandom and Math::Random::ISAAC::XS modules are installed in the application PERL5LIB path. References ---------- https://github.com/PerlDancer/Dancer2/blob/v2.1.0/lib/Dancer2/Core/Role/SessionFactory.pm#L142 https://www.cve.org/CVERecord?id=CVE-2026-5080
