What’s Vulnerable › Vulnerabilities

CVE-2017-20285: YAML versions before 1.30 for Perl allow a loaded document to trigger the DESTROY method of arbitrary classes

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-05 · updated 2026-10-06
• Weakness: CWE-502

Description

YAML versions before 1.30 for Perl allow a loaded document to trigger the DESTROY method of arbitrary classes. A perl/hash:Class tag blesses a hash into the class it names. The document supplies the object's fields, and Perl calls DESTROY when it goes out of scope. What DESTROY does depends on the classes the process has loaded. With File::Temp::Dir from core Perl, it can delete a directory tree the document names.

Affected products

• YAML: before 1.30 — fixed in 1.30

How to fix

Upgrade to a fixed version: YAML 1.30. Check the vendor advisory for mitigations.

References

• https://github.com/ingydotnet/yaml-pm/commit/471314bbdcbd62077eea32755929122aa8bd00a3.patch
• https://github.com/ingydotnet/yaml-pm/commit/7736f38bd02e4f9f77d5468721e3be3d7b34a8ec.patch
• https://github.com/ingydotnet/yaml-pm/issues/176
• https://metacpan.org/release/TINITA/YAML-1.30/changes
• http://www.openwall.com/lists/oss-security/2026/10/05/8

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