CVE-2026-13577Dancer2 versions before 2.2.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable
- 8.2HighCVSS base score
- 0.57%Exploitation in 30 daysEPSS · top 52% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By CPANSec
- 22 days later
· 22 days later
Published
- 2 months later
· 2 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | High8.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H |
| NVDNVD · Deferred | 3.1 | High8.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.57% · top 52% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.2.
Affected products
Dancer2
- affected < 2.2.0
What to do
Solution: Upgrade to Davcer2 2.2.0 or later.
Workaround: For deployments that cannot upgrade, ensure Crypt::URandom and Math::Random::ISAAC::XS modules are installed in the application PERL5LIB path.
References
References5
- https://metacpan.org/release/CROMEDOME/Dancer2-2.2.0/changes (opens in a new tab)release-notes
- https://github.com/PerlDancer/Dancer2/issues/1807 (opens in a new tab)issue-tracking
- https://github.com/PerlDancer/Dancer2/pull/1804 (opens in a new tab)issue-tracking
- https://github.com/PerlDancer/Dancer2/blob/v2.1.0/lib/Dancer2/Core/Role/SessionFactory.pm#L142 (opens in a new tab)
- https://www.cve.org/CVERecord?id=CVE-2026-5080 (opens in a new tab)related
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-45896 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-13577)Record last updated .