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.
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.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
Upgrade to YAML 1.28 or later.
Workaround
For deployments that cannot upgrade to YAML 1.28, set $YAML::LoadBlessed = 0 before loading untrusted input. The option exists from YAML 1.25 and gates glob loading too.
References
History
Mon, 05 Oct 2026 07:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| 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 | |
| Weaknesses | CWE-502 CWE-914 |
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| References |
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Projects
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Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-10-05T06:50:17.532Z
Reserved: 2026-09-21T21:17:21.642Z
Link: CVE-2019-25777
No data.
Status : Received
Published: 2026-10-05T07:16:29.557
Modified: 2026-10-05T07:16:29.557
Link: CVE-2019-25777
No data.
OpenCVE Enrichment
Updated: 2026-10-05T09:30:10Z