CPANSA-YAML-Syck-2026-13713: YAML-Syck vulnerability
| Publisher | giterlizzi | Document category | csaf_security_advisory |
|---|---|---|---|
| Initial release date | 2026-07-16T00:00:00 | Engine | CSAF Perl Toolkit 0.26 |
| Current release date | 2026-07-16T00:00:00 | Build Date | |
| Current version | 1 | Status | final |
| CVSS v3.1 Base Score | 6.2 | Severity | |
| Original language | Language | en | |
| Also referred to | |||
Vulnerability Description
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.
Vulnerabilities
CVE-2026-13713
Vulnerability 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.
| Weakness | CWE-415 : Double Free |
|---|
Product status
Known affected
| Product | Score | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| YAML-Syck less than 1.47 |
|
Fixed
- YAML-Syck greater than or equal 1.47
giterlizzi
Namespace: https://github.com/giterlizzi/
gdt@cpan.org
References
- CPANSA-YAML-Syck-2026-13713 JSON self
https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa-yaml-syck-2026-13713.json - https://github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d8b.patch external
https://github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d8b.patch - https://metacpan.org/release/TODDR/YAML-Syck-1.47/changes external
https://metacpan.org/release/TODDR/YAML-Syck-1.47/changes - CVE-2026-13713 (NVD) external
https://nvd.nist.gov/vuln/detail/CVE-2026-13713
Revision history
| Version | Date of the revision | Summary of the revision |
|---|---|---|
| 1 | Thu Jul 16 00:00:00 2026 | First release |
Sharing rules
TLP:WHITE
For the TLP version see: https://www.first.org/tlp/