Skip to content
Fencer Vulns
medium 6.2

CVE-2026-13713 json

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

published 2026-07-16 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-45052

cvss
6.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

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.

Patch / fix

  • TODDR YAML::Syck 1.47
  • libyaml-syck-perl Debian 12 1.34-2+deb12u3
  • libyaml-syck-perl Debian 13 1.34-2+deb13u3
  • libyaml-syck-perl Debian 14 1.47-1

debian advisories DEBIAN-CVE-2026-13713

  • perl-YAML-Syck RHEL 8 1.30-7.el8_10

red hat advisories RHSA-2026:67269

  • perl-YAML-Syck openSUSE Leap 16.0 1.470.0-bp160.1.1
  • perl-YAML-Syck openSUSE Tumbleweed 1.470.0-1.1

opensuse advisories openSUSE-SU-2026:21497-1openSUSE-SU-2026:11299-1

  • perl-YAML-Syck AlmaLinux 8 1.30-7.el8_10

almalinux advisories ALSA-2026:67269

  • perl-YAML-Syck Rocky Linux 8 1.30-7.el8_10

rocky linux advisories RLSA-2026:67269

  • perl-yaml-syck Alpine 3.24 1.47-r0

alpine advisories ALPINE-CVE-2026-13713

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-13713 updated cvss 7.5

YAML-Syck: YAML::Syck: Denial of Service via crafted YAML document

  • Red Hat Enterprise Linux 6 perl-YAML-Syck Red Hat Enterprise Linux 7 perl-YAML-Syck
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux CRB (v. 8) perl-YAML-Syck 1.30-7.el8_10
    fixed: vendor fix RHSA-2026:67269

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.2 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 6.2 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • TODDR YAML::Syck

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.