CVE-2026-13577 Affecting libdancer2-perl package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-ECHOLATEST-LIBDANCER2PERL-18021738
- published20 Jul 2026
- disclosed20 Jul 2026
Introduced: 20 Jul 2026
CVE-2026-13577 (opens in a new tab)How to fix?
There is no fixed version for Echo:latest libdancer2-perl.
NVD Description
Note: Versions mentioned in the description apply only to the upstream libdancer2-perl package and not the libdancer2-perl package as distributed by Echo.
See How to fix? for Echo:latest relevant fixed versions and status.
Dancer2 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.
References
- https://advisory.echohq.com/cve/CVE-2026-13577
- https://www.cve.org/CVERecord?id=CVE-2026-13577
- 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
- https://github.com/PerlDancer/Dancer2/issues/1807
- https://github.com/PerlDancer/Dancer2/pull/1804
- https://metacpan.org/release/CROMEDOME/Dancer2-2.2.0/changes