CVE-2026-13713 Affecting libyaml-syck-perl package, versions <1.34-2+deb13u3


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.13% (4th percentile)

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  • Snyk IDSNYK-DEBIAN13-LIBYAMLSYCKPERL-18003168
  • published17 Jul 2026
  • disclosed16 Jul 2026

Introduced: 16 Jul 2026

NewCVE-2026-13713  (opens in a new tab)

How to fix?

Upgrade Debian:13 libyaml-syck-perl to version 1.34-2+deb13u3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libyaml-syck-perl package and not the libyaml-syck-perl package as distributed by Debian. See How to fix? for Debian:13 relevant fixed versions and status.

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.

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.

CVSS Base Scores

version 3.1