CVE-2026-4177

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

0.43% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 35.6% 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.

Published

2026-03-16 22:30Z5 MO AGO

Last updated

2026-07-15 00:58Z1 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

• 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