{"id":"UBUNTU-CVE-2026-13577","details":"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.","modified":"2026-09-24T02:01:39.659514003Z","published":"2026-07-20T08:16:00Z","upstream":["CVE-2026-13577"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-13577"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-13577"},{"type":"REPORT","url":"https://lists.security.metacpan.org/cve-announce/msg/41975698/"}],"affected":[{"package":{"name":"libdancer2-perl","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/libdancer2-perl?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.160003+dfsg-1","0.163000+dfsg-1","0.166001+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.166001+dfsg-1","binary_name":"libdancer2-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13577.json"}},{"package":{"name":"libdancer2-perl","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/libdancer2-perl?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.205000+dfsg-1","0.205002+dfsg-1","0.205002+dfsg-2"],"ecosystem_specific":{"binaries":[{"binary_name":"libdancer2-perl","binary_version":"0.205002+dfsg-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13577.json"}},{"package":{"name":"libdancer2-perl","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/libdancer2-perl?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.208001+dfsg-1","0.208002+dfsg-1","0.300000+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.300000+dfsg-1","binary_name":"libdancer2-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13577.json"}},{"package":{"name":"libdancer2-perl","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/libdancer2-perl?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.300005+dfsg-1","0.301004+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libdancer2-perl","binary_version":"0.301004+dfsg-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13577.json"}},{"package":{"name":"libdancer2-perl","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/libdancer2-perl?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.400001+dfsg-1","1.0.0+dfsg-1","1.1.0+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libdancer2-perl","binary_version":"1.1.0+dfsg-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13577.json"}},{"package":{"name":"libdancer2-perl","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/libdancer2-perl?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.2+dfsg-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libdancer2-perl","binary_version":"1.1.2+dfsg-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13577.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}