CVE-2017-20285

Summary

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 Software

VendorProductVersion RangeStatus
0 < 1.30affected

Weaknesses

  • CWE-502: CWE-502 Deserialization of Untrusted Data
  • CWE-470: CWE-470 Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')

Workarounds

For deployments that cannot upgrade to YAML 1.30, set $YAML::LoadBlessed = 0 before loading untrusted input. The option exists from YAML 1.25.

ADP Enrichment

CVE Program Container

Additional References

References