---
id: CVE-2019-25777
title: >-
  YAML versions before 1.27_001 for Perl allow a loaded perl/glob document to
  replace any package variable, which can lead to arbitrary code execution.


  A perl/glob document names a package and a symbol, and supplies the value
  assigned to …
summary: >-
  YAML versions before 1.27_001 for Perl allow a loaded perl/glob document to
  replace any package variable, which can lead to arbitrary code execution.


  A perl/glob document names a package and a symbol, and supplies the value
  assigned to …
severity: none
cwe:
  - CWE-502
  - CWE-914
product: YAML
affected:
  - YAML < 1.27_001
published: '2026-10-05'
updated: '2026-10-05'
sourceUpdated: '2026-10-05T07:16:29.557'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2019-25777'
references:
  - url: >-
      https://github.com/ingydotnet/yaml-pm/commit/bace96b5e6661d521c7c515c94a09e081c911fce.patch
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://github.com/ingydotnet/yaml-pm/issues/212'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://metacpan.org/release/TINITA/YAML-1.28/changes'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-05T07:14:48.255Z'
---

## Overview

YAML versions before 1.27_001 for Perl allow a loaded perl/glob document to replace any package variable, which can lead to arbitrary code execution.

A perl/glob document names a package and a symbol, and supplies the value assigned to it. Nothing restricts the name, so the target can be @INC or YAML's own load options.

A perl/glob document that sets $YAML::LoadCode or $YAML::UseCode turns on code loading, which is off by default, for every later Load() in the process. A perl/code document is then passed to a string eval, so an attacker who supplies two documents to separate Load() calls in one process can execute arbitrary Perl code.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.