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Fencer Vulns
critical 9.1

CVE-2026-57075 json

YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec

published 2026-07-16 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-45054

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec.

The base64 decoder in the bundled libsyck indexes the 256-entry static table b64_xtable with a signed char, so any !!binary byte >= 0x80 sign-extends to a negative index and reads before the table. The decoder receives the raw bytes of any !!binary node, a standard YAML type not gated by $LoadBlessed or $LoadCode, so it is reached on the default Load path.

Any caller that runs Load or LoadFile on an untrusted document containing a !!binary scalar with a high-bit byte triggers the read, and the value read can surface in the decoded result.

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-2026-57075

  • 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-2026-57075

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-2026-57075 updated cvss 6.5

YAML::Syck: YAML::Syck: Information disclosure via out-of-bounds read in base64 decoder

  • 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
yes
Technical impact
total
Assessed
3 mo ago

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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.