What’s Vulnerable › Vulnerabilities

CVE-2025-40908: YAML-LibYAML prior to 0.903.0 for Perl uses 2-args open, allowing existing files to be modified

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-06-01 · updated 2026-06-17
• Weakness: CWE-552

Description

YAML-LibYAML prior to 0.903.0 for Perl uses 2-args open, allowing existing files to be modified

Affected products

• Ingydotnet Yaml-Libyaml: before 0.903.0 — fixed in 0.903.0

How to fix

Upgrade to a fixed version: Ingydotnet Yaml-Libyaml 0.903.0. Check the vendor advisory for mitigations.

References

• https://github.com/ingydotnet/yaml-libyaml-pm/issues/120
• https://github.com/ingydotnet/yaml-libyaml-pm/pull/121
• https://github.com/ingydotnet/yaml-libyaml-pm/pull/122

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