YAML::Syck versions before 1.47 for Perl allow a use-after-free and double-free via an anchor node freed while still on the parser value stack

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Summary

CVECVE-2026-13713
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-16 22:16:59 UTC
Updated2026-07-17 04:16:50 UTC
DescriptionYAML::Syck versions before 1.47 for Perl allow a use-after-free and double-free via an anchor node freed while still on the parser value stack. In the bundled libsyck, when an anchor name is redefined or removed, syck_hdlr_add_anchor and syck_hdlr_remove_anchor free the node stored under that name with syck_free_node. That node can still be live on the parser's value stack, so syck_hdlr_add_node reaches it again and frees it a second time. On a normal build the 48-byte node chunk is freed twice and the interpreter aborts. Anchors need no special flags, so this is reached on the default Load path, and a 7-byte document that redefines an anchor triggers it. Any caller that runs Load or LoadFile on an untrusted document that redefines an anchor mid-parse crashes the interpreter, a denial of service.

Risk And Classification

Problem Types: CWE-415 | CWE-416 | CWE-416 CWE-416 Use After Free | CWE-415 CWE-415 Double Free

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA TODDR YAMLSyck affected 1.47 custom Not specified

References

ReferenceSourceLinkTags
metacpan.org/release/TODDR/YAML-Syck-1.47/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
www.openwall.com/lists/oss-security/2026/07/17/1 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d... 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

Solutions

CNA: Upgrade to YAML-Syck 1.47 or later.

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