VulnerabilityDeferred

CVE-2026-13577

Dancer2 versions through 2.1.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable.

HIGH 8.2EPSS 0.45%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.45%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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 3.1: 8.2 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
EPSS: 0.45% probability · 38th percentile
CISA KEV: Not listed
Weakness: CWE-338, CWE-340
Source: 9b29abf9-4ab0-4765-b253-1875cd9b441e

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.