{"id":"UBUNTU-CVE-2026-13713","details":"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.","modified":"2026-07-29T07:53:20Z","published":"2026-07-16T22:16:00Z","upstream":["CVE-2026-13713"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-13713"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-13713"},{"type":"REPORT","url":"https://www.openwall.com/lists/oss-security/2026/07/17/1"},{"type":"REPORT","url":"https://github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d8b.patch"},{"type":"REPORT","url":"https://metacpan.org/release/TODDR/YAML-Syck-1.47/changes"},{"type":"REPORT","url":"http://www.openwall.com/lists/oss-security/2026/07/17/1"}],"affected":[{"package":{"name":"libyaml-syck-perl","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.27-2build2","1.29-1","1.29-1build1","1.29-1ubuntu0.16.04.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.29-1ubuntu0.16.04.1~esm1","binary_name":"libyaml-syck-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13713.json"}},{"package":{"name":"libyaml-syck-perl","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.29-1build3","1.29-1ubuntu0.18.04.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libyaml-syck-perl","binary_version":"1.29-1ubuntu0.18.04.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13713.json"}},{"package":{"name":"libyaml-syck-perl","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.31-1","1.31-1build1","1.31-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libyaml-syck-perl","binary_version":"1.31-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13713.json"}},{"package":{"name":"libyaml-syck-perl","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.34-1build1","1.34-1build2","1.34-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.34-1ubuntu0.1~esm1","binary_name":"libyaml-syck-perl"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13713.json"}},{"package":{"name":"libyaml-syck-perl","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.34-2","1.34-2build1","1.34-2build2","1.34-2build3","1.34-2ubuntu0.24.04.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libyaml-syck-perl","binary_version":"1.34-2ubuntu0.24.04.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13713.json"}},{"package":{"name":"libyaml-syck-perl","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.34-3","1.34-4","1.36-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libyaml-syck-perl","binary_version":"1.36-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13713.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}