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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2019-25777
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-05 07:16:29 UTC
Updated2026-10-06 17:17:09 UTC
DescriptionYAML 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.

Risk And Classification

Primary CVSS: v3.1 7.3 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

EPSS: 0.002210000 probability, percentile 0.115470000 (date 2026-10-06)

Problem Types: CWE-502 | CWE-914 | CWE-914 CWE-914 Improper Control of Dynamically-Identified Variables | CWE-502 CWE-502 Deserialization of Untrusted Data

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.3HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.3HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

References

ReferenceSourceLinkTags
www.openwall.com/lists/oss-security/2026/10/05/7 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
github.com/ingydotnet/yaml-pm/issues/212 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
metacpan.org/release/TINITA/YAML-1.28/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
github.com/ingydotnet/yaml-pm/commit/bace96b5e6661d521c7c515c94a09e081c9... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2019-04-27T00:00:00.000ZIssue reported.
CNA2019-04-27T00:00:00.000ZVersion 1.27_001 released with fix.
CNA2019-04-28T00:00:00.000ZVersion 1.28 released with fix.
CNA2022-06-27T00:00:00.000ZIssue added as CPANSA-YAML-2019-01 in the CPAN::Audit database.
CNA2026-09-21T00:00:00.000ZCVE number reserved.

Solutions

CNA: Upgrade to YAML 1.28 or later.

Workarounds

CNA: 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.

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