CVE-2026-13713
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.
Does this matter?
Lower severity and a low EPSS score (0.18%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.2 MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.18% probability · 7th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-415, CWE-416
- Source
- 9b29abf9-4ab0-4765-b253-1875cd9b441e
EPSS 0.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.