Bug 2509105

Summary:	CVE-2026-13577 perl-Dancer2: Dancer2: Predictable session IDs allow system access [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Tomas Hoger <thoger>
Component:	perl-Dancer2	Assignee:	Emmanuel Seyman <emmanuel>
Status:	ON_QA ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	45	CC:	emmanuel, perl-devel
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["d1449e56-3b9c-42f6-aa00-ca0e5cc3add7"]}
Fixed In Version:		Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2502710

Description Tomas Hoger 2026-07-30 06:28:32 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Dancer2 versions through 2.1.0 for Perl generate insecure session ids when CSPRNG modules are unavailable.

Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id when both Math::Random::ISAAC::XS and Crypt::URandom are unavailable.

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.

Comment 1 Aoife Moloney 2026-08-17 15:41:00 UTC

This bug appears to have been reported against 'rawhide' during the Fedora Linux 45 development cycle.
Changing version to 45.

Comment 2 Fedora Update System 2026-09-06 22:58:56 UTC

FEDORA-2026-d0bededb87 (perl-Dancer2-1.1.2-4.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-d0bededb87

Comment 3 Fedora Update System 2026-09-06 22:58:56 UTC

FEDORA-2026-28c5da9193 (perl-Dancer2-2.1.0-3.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-28c5da9193

Comment 4 Fedora Update System 2026-09-07 01:10:07 UTC

FEDORA-2026-28c5da9193 has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-28c5da9193`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-28c5da9193

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2026-09-07 01:23:54 UTC

FEDORA-2026-d13a2593b1 has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-d13a2593b1`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-d13a2593b1

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 6 Fedora Update System 2026-09-07 01:42:57 UTC

FEDORA-2026-d0bededb87 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-d0bededb87`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-d0bededb87

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.