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Fencer Vulns
high 7.8

CVE-2026-57076 json

YAML::Syck versions before 1.47 for Perl allow a heap use-after-free via an anchor name reused as an anchors-table key in syck_hdlr_add_anchor

published 2026-07-16 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-45055

cvss
7.8
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 6%
public exploits
0
none known

Summary

YAML::Syck versions before 1.47 for Perl allow a heap use-after-free via an anchor name reused as an anchors-table key in syck_hdlr_add_anchor.

In the bundled libsyck an anchor name allocated by syck_strndup is stored both as node->anchor, freed when the node is freed, and as the key in the parser's anchors table. Freeing the node frees the shared key, and a later anchor redefinition makes st_delete compare against the freed key, so st_strcmp reads freed heap memory. Anchors are a standard YAML feature and need no special flags, so this is reached on the default Load path.

Any caller that runs Load or LoadFile on an untrusted document that redefines an anchor reaches the read of freed memory.

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-2026-57076

  • 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 Alpine 3.24 1.47-r0

alpine advisories ALPINE-CVE-2026-57076

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-2026-57076 updated cvss 6.3

YAML-Syck: YAML::Syck: Heap use-after-free via anchor name reuse

  • 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 8 perl-YAML-Syck
    affected: workaround, no fix available “Fix deferred”

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
total
Assessed
3 mo ago

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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.