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Fedora 44 perl-Dancer2 Major Deserialization Vulnerability 2026

Linuxsecurity •LinuxSecurity Advisories • September 29, 2026

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Dancer2 is the new generation of Dancer, the lightweight web-framework for

Perl. It is a complete rewrite based on Moo and is meant to be easy and fun.

Dancer2::Serializer::YAML::deserialize handed request bodies straight to YAML::Load. A body tagged !!perl/hash:Some::Class therefore instantiated an arbitrary blessed object — the entry point for DESTROY/AUTOLOAD/overload gadget chains — and !!perl/code could ask for a string eval. deserialize now sets $YAML::LoadBlessed = 0 and $YAML::LoadCode = 0 itself (localised) before loading, rather than relying on YAML.pm's ambient defaults, and the minimum YAML is raised to 1.30.

* Sun Sep 20 2026 Emmanuel Seyman - 2.2.1-1 - Update to 2.2.1 - Downsize version check to make no check the default

Fedora Update Notification FEDORA-2026-3b893ccf2d 2026-09-29 01:05:47.911295+00:00 Name : perl-Dancer2 Product : Fedora 44 Version : 2.2.1 Release : 1.fc44 URL : Summary : Lightweight yet powerful web application framework Description : Dancer2 is the new generation of Dancer, the lightweight web-framework for Perl. It is a complete rewrite based on Moo and is meant to be easy and fun.

This update can be installed with the "dnf" update program. Use su -c 'dnf upgrade --advisory FEDORA-2026-3b893ccf2d' at the command line. For more information, refer to the dnf documentation available at

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Critical Deserialization Vulnerability in Fedora 44 and 45 perl-Dancer2 A major deserialization vulnerability has been identified in the perl-Dancer2 framework affecting Fedora 44 and 45. CISA has confirmed exploitation of this flaw, which allows arbitrary object instantiation through YAML deserialization. The vulnerability arises from the Dancer2::Serializer::YAML::deserialize method, which improperly handles request bodies. This vulnerability is particularly concerning as it can lead to the execution of arbitrary code. The affected versions are perl-Dancer2 2.2.1 in both Fedora 44 and 45. Users are urged to apply the available patches immediately to mitigate the risk. The updates set $YAML::LoadBlessed and $YAML::LoadCode to 0 before loading, addressing the security issue. The updates can be installed using the dnf package manager. As of today, both updates have been released and are available for installation. 2 sources 73

Extracted Entities

Fedora 44 perl-Dancer2 Major Deserialization Vulnerability 2026

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Extracted Entities

Attack Types (1)

CWE Weaknesses (1)

Domains (1)

MITRE ATT&CK (1)

Platforms (1)