CVE-2017-20285 YAML versions before 1.30 for Perl allow a loaded document to trigger the DESTROY method of arbitrary classes
Attackers can execute arbitrary code or delete files by crafting malicious YAML documents that trigger unsafe DESTROY methods in Perl applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2017-20285?
CVE-2017-20285 is a critical unsafe deserialization vulnerability, published on 5 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2017-20285?
How do I fix CVE-2017-20285?
Upgrade to a fixed version.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2017-20285 being exploited?
There is no known exploitation of CVE-2017-20285 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2017-20285, GHSA-c454-fc94-q86x, UBUNTU-CVE-2017-20285.