01 Record

CVE-2026-4177

YAML::Syck versions through 1.36 for Perl has several potential security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter

CriticalPUBLISHEDCNA: CPANSec

CNA base score9.1 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

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02 Description

YAML::Syck versions through 1.36 for Perl has several potential security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter

03 Exploitation and scoring

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.44% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 38.4% of scored records. A rank, not a probability.

NVD base score

9.1 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-07-15.

Red Hat severity

Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2026-03-16 22:30Z7 MO AGO

Last updated

2026-07-15 00:58Z3 MO AGO

Reserved

2026-03-14

Assigning CNA

CPANSec

Record state

PUBLISHED

Severity

Critical (CVSS 9.1)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Weaknesses

CWE-122Heap-based Buffer OverflowVariant
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')Base

Data version

5.2

Document digest

56bb6b49b3959b331679438e0e7104ca84a4dd1505419464ca6f34834d3a7490

05 Affected products

VendorProductVersionsPlatforms

TODDRYAML::Syck0 to 1.36—

06 References

github.comhttps://github.com/cpan-authors/YAML-Syck/commit/e8844a31c8cf0052914b198fc784ed4e6b8ae69e.patchpatch
metacpan.orghttps://metacpan.org/release/TODDR/YAML-Syck-1.37_01/changes#L21release-notes
www.openwall.comhttp://www.openwall.com/lists/oss-security/2026/03/16/6
access.redhat.comhttps://access.redhat.com/security/cve/CVE-2026-4177vdb-entryx_refsource_REDHAT
bugzilla.redhat.comRHBZ#2448277https://bugzilla.redhat.com/show_bug.cgi?id=2448277issue-trackingx_refsource_REDHAT
security.access.redhat.comhttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4177.jsonx_sadp-csaf-vex
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:8311vendor-advisoryx_refsource_REDHAT
access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:6470vendor-advisoryx_refsource_REDHAT

07 Remediation

Upgrade to version 1.37 or higher.

08 Fixed in

AlmaLinux 8

perl-YAML-Syck
Fixed in 1.30-6.el8_10

CloudLinux 8

perl-YAML-Syck
Fixed in 1.30-6.el8_10

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Debian 12

libyaml-syck-perl
Fixed in 1.34-2+deb12u2

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

libyaml-syck-perl
Fixed in 1.34-2+deb13u2

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

libyaml-syck-perl
Fixed in 1.36-2

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.