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

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Summary

CVECVE-2026-4177
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-16 23:16:21 UTC
Updated2026-07-15 02:22:39 UTC
DescriptionYAML::Syck versions through 1.36 for Perl has several potential security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter. The heap overflow occurs when class names exceed the initial 512-byte allocation. The base64 decoder could read past the buffer end on trailing newlines. strtok mutated n->type_id in place, corrupting shared node data. A memory leak occurred in syck_hdlr_add_anchor when a node already had an anchor. The incoming anchor string 'a' was leaked on early return.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from ADP

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

EPSS: 0.004290000 probability, percentile 0.347460000 (date 2026-07-16)

Problem Types: CWE-122 | CWE-120 | CWE-122 CWE-122 Heap-based Buffer Overflow | CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
3.1ADPCVSS7.3HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.3HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Toddr Yaml \ syck All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA TODDR YAMLSyck affected 1.36 custom Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support unaffected 0:1.27-3.el7_9.1 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8 unaffected 0:1.30-6.el8_10 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 6 Not specified Not specified

References

ReferenceSourceLinkTags
metacpan.org/release/TODDR/YAML-Syck-1.37_01/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org Release Notes
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4177.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
access.redhat.com/errata/RHSA-2026:6470 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
www.openwall.com/lists/oss-security/2026/03/16/6 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com Mailing List, Third Party Advisory
access.redhat.com/errata/RHSA-2026:8311 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/security/cve/CVE-2026-4177 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
github.com/cpan-authors/YAML-Syck/commit/e8844a31c8cf0052914b198fc784ed4... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com Patch
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Todd Rinaldo (en)

Additional Advisory Data

SourceTimeEvent
ADP2026-03-16T23:01:43.396ZReported to Red Hat.
ADP2026-03-16T22:30:25.367ZMade public.

Solutions

CNA: Upgrade to version 1.37 or higher.

ADP: RHSA-2026:8311: Red Hat Enterprise Linux Server Optional (v. 7 ELS)

ADP: RHSA-2026:6470: Red Hat Enterprise Linux CRB (v. 8)

Workarounds

ADP: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

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