High
libdancer2-perl — security advisory
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.
- Products
- libdancer2-perl
- Affected versions
- 0.160003+dfsg-1, 0.163000+dfsg-1, 0.166001+dfsg-1, 0.205000+dfsg-1, 0.205002+dfsg-1, 0.205002+dfsg-2, 0.208001+dfsg-1, 0.208002+dfsg-1, 0.300000+dfsg-1, 0.300005+dfsg-1, 0.301004+dfsg-1, 0.400001+dfsg-1, 1.0.0+dfsg-1, 1.1.0+dfsg-1, 1.1.2+dfsg-1, 2.1.0-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-13577
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:40 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-13577
libdancer2-perl
Fixed versions: Not specified
libdancer2-perl
Fixed versions: Not specified
libdancer2-perl
Fixed versions: Not specified
libdancer2-perl
Fixed versions: Not specified
libdancer2-perl
Fixed versions: Not specified
libdancer2-perl
Fixed versions: Not specified
libdancer2-perl
Fixed versions: Not specified
Complete source record
{
"id": "a8a38cca9d07bd2f462e5a414df008a1280ec81249128b9b4af1a53f6045742e",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-13577",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-13577",
"summary": "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.",
"evidence": "osv:UBUNTU-CVE-2026-13577",
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{
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],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-13577",
"aliases": [
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],
"metrics": [
{
"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"
}
],
"affected": [
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"type": "ECOSYSTEM",
"events": [
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"package": {
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"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
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"database_specific": {
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"ecosystem_specific": {
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{
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"package": {
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"purl": "pkg:deb/ubuntu/libdancer2-perl?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"0.205000+dfsg-1",
"0.205002+dfsg-1",
"0.205002+dfsg-2"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
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{
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"package": {
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"purl": "pkg:deb/ubuntu/libdancer2-perl?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
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"versions": [
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"0.301004+dfsg-1"
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],
"modified": "2026-10-17T12:58:45.460494622Z",
"provider": "osv",
"upstream": [
"CVE-2026-13577"
],
"references": [
"https://ubuntu.com/security/CVE-2026-13577",
"https://www.cve.org/CVERecord?id=CVE-2026-13577",
"https://lists.security.metacpan.org/cve-announce/msg/41975698/"
]
},
"related_cves": [
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"evidence": "/upstream"
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],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359008,
"published_at": "2026-07-20T08:16:00+00:00"
}