23 Oct 2026 15:48:27 UTC
Dancer2 versions before 2.2.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable
cve-program · CVE-2026-13577 · Published
CVE-2026-13577
Dancer2 · Vulnerability
cve-program · severity unknownCVSS unknownCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-13577
PublishedDancer2 versions before 2.2.0 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.
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