# 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.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Oct 2026
- **Updated:** 6 Oct 2026
- **Also known as:** DEBIAN-CVE-2017-20285, GHSA-c454-fc94-q86x, UBUNTU-CVE-2017-20285

## 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.

Weakness: CWE-502 (Deserialization of Untrusted Data), CWE-470 (Use of Externally-Controlled Input to Select Classes or Code)

## Which versions are affected by CVE-2017-20285?


## How do I fix CVE-2017-20285?

Upgrade to a fixed version.

## Is CVE-2017-20285 being exploited?

There is no known exploitation of CVE-2017-20285 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-20285 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2017-20285 in the wild and no public exploit code.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2017-20285/ (Markdown: https://insights.sbomify.com/CVE-2017-20285/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-20285
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-20285
- OSV: https://osv.dev/vulnerability/CVE-2017-20285

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From sbomify Insights: https://insights.sbomify.com/CVE-2017-20285/
Summaries are generated and may contain mistakes; the official description above is the record.