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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-13577
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-20 08:16:28 UTC
Updated2026-07-22 12:17:09 UTC
DescriptionDancer2 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.

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

EPSS: 0.002580000 probability, percentile 0.174250000 (date 2026-07-22)

Problem Types: CWE-338 | CWE-340 | CWE-340 CWE-340 Generation of Predictable Numbers or Identifiers | CWE-338 CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA CROMEDOME Dancer2 affected 2.1.0 custom Not specified

References

ReferenceSourceLinkTags
www.cve.org/CVERecord 9b29abf9-4ab0-4765-b253-1875cd9b441e www.cve.org
github.com/PerlDancer/Dancer2/blob/v2.1.0/lib/Dancer2/Core/Role/SessionF... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Workarounds

CNA: Ensure Crypt::URandom and Math::Random::ISAAC::XS modules are installed in the application PERL5LIB path.

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