CVE-2026-13713

NameCVE-2026-13713
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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1142267

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
libyaml-syck-perl (PTS)bullseye1.34-1vulnerable
bullseye (security)1.34-1+deb11u1vulnerable
bookworm, bookworm (security)1.34-2+deb12u2vulnerable
trixie (security), trixie1.34-2+deb13u2vulnerable
forky1.36-3vulnerable
sid1.47-1vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
libyaml-syck-perlsource(unstable)(unfixed)1142267

Notes

https://www.openwall.com/lists/oss-security/2026/07/17/1
Fixed by: https://github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d8b (1.47)

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