AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

{"timestamp":"2026-07-20T13:05:03.182340Z","id":"CVE-2026-13577","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}

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.

CWE-338

CWE-340

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

[{"vendor":"CROMEDOME","product":"Dancer2","defaultStatus":"unaffected","collectionURL":"https://cpan.org/modules","packageName":"Dancer2","programFiles":["lib/Dancer2/Core/Role/SessionFactory.pm"],"programRoutines":[{"name":"Dancer2::Core::Role::SessionFactory::generate_id"}],"repo":"https://github.com/PerlDancer/Dancer2","versions":[{"version":"0","lessThanOrEqual":"2.1.0","versionType":"custom","status":"affected"}]}]