ubuntu-cve-2026-13577
Vulnerability from osv_ubuntu
Published
2026-07-20 08:16
Modified
2026-07-29 07:53
Summary
Details
Dancer2 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.
Severity
8.2 (High)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libdancer2-perl",
"binary_version": "0.166001+dfsg-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:16.04:LTS",
"name": "libdancer2-perl",
"purl": "pkg:deb/ubuntu/libdancer2-perl@0.166001+dfsg-1?arch=source\u0026distro=xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.160003+dfsg-1",
"0.163000+dfsg-1",
"0.166001+dfsg-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libdancer2-perl",
"binary_version": "0.205002+dfsg-2"
}
]
},
"package": {
"ecosystem": "Ubuntu:18.04:LTS",
"name": "libdancer2-perl",
"purl": "pkg:deb/ubuntu/libdancer2-perl@0.205002+dfsg-2?arch=source\u0026distro=bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.205000+dfsg-1",
"0.205002+dfsg-1",
"0.205002+dfsg-2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libdancer2-perl",
"binary_version": "0.300000+dfsg-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:20.04:LTS",
"name": "libdancer2-perl",
"purl": "pkg:deb/ubuntu/libdancer2-perl@0.300000+dfsg-1?arch=source\u0026distro=focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.208001+dfsg-1",
"0.208002+dfsg-1",
"0.300000+dfsg-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libdancer2-perl",
"binary_version": "0.301004+dfsg-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "libdancer2-perl",
"purl": "pkg:deb/ubuntu/libdancer2-perl@0.301004+dfsg-1?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.300005+dfsg-1",
"0.301004+dfsg-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libdancer2-perl",
"binary_version": "1.1.0+dfsg-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "libdancer2-perl",
"purl": "pkg:deb/ubuntu/libdancer2-perl@1.1.0+dfsg-1?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.400001+dfsg-1",
"1.0.0+dfsg-1",
"1.1.0+dfsg-1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libdancer2-perl",
"binary_version": "1.1.2+dfsg-1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "libdancer2-perl",
"purl": "pkg:deb/ubuntu/libdancer2-perl@1.1.2+dfsg-1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.1.2+dfsg-1"
]
}
],
"aliases": [],
"details": "Dancer2 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.",
"id": "UBUNTU-CVE-2026-13577",
"modified": "2026-07-29T07:53:20Z",
"published": "2026-07-20T08:16:00Z",
"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/"
}
],
"related": [],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-13577"
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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