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[USN-8925-1] YAML-LibYAML vulnerabilities

Posted on 14 October 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8925-1
October 14, 2026

libyaml-perl vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in YAML-LibYAML.

Software Description:
- libyaml-perl: Perl interface to libyaml, a YAML implementation

Details:

Dominique Dumont discovered that YAML-LibYAML did not correctly handle
certain reflection operations. If a user or system were tricked into
opening a specially crafted file, an attacker could possibly use this issue
to delete files. This issue only affected Ubuntu 16.04 LTS and Ubuntu 18.04
LTS. (CVE-2017-20285)

It was discovered that YAML-LibYAML did not correctly handle parsing
certain documents. If a user or automated system were tricked into opening
a specially crafted file, an attacker could possibly use this issue to
execute arbitrary code. This issue only affected Ubuntu 16.04 LTS and
Ubuntu 18.04 LTS. (CVE-2019-25777)

It was discovered that YAML-LibYAML contained a regular expression
susceptible to catastrophic backtracking. If a user or automated system
were tricked into opening a specially crafted file, an attacker could
possibly use this issue to cause a denial of service. (CVE-2026-63676)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
libyaml-perl 1.31-1ubuntu0.26.04.1~esm1
Available with Ubuntu Pro

Ubuntu 24.04 LTS
libyaml-perl 1.31-1ubuntu0.24.04.1

Ubuntu 22.04 LTS
libyaml-perl 1.30-1ubuntu0.22.04.1

Ubuntu 20.04 LTS
libyaml-perl 1.30-1ubuntu0.20.04.1~esm1
Available with Ubuntu Pro

Ubuntu 18.04 LTS
libyaml-perl 1.24-1ubuntu0.1~esm1
Available with Ubuntu Pro

Ubuntu 16.04 LTS
libyaml-perl 1.15-1ubuntu0.1~esm1
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8925-1
CVE-2017-20285, CVE-2019-25777, CVE-2026-63676

Package Information:
https://launchpad.net/ubuntu/+source/libyaml-perl/1.31-1ubuntu0.24.04.1
https://launchpad.net/ubuntu/+source/libyaml-perl/1.30-1ubuntu0.22.04.1

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