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CVE-2026-4177

33
FAUCET Score

CVE-2026-4177 is a critical vulnerability affecting YAML::Syck versions through 1.36 for Perl, primarily a high-severity heap buffer overflow in the YAML emitter, alongside other issues like memory leaks. Rated 9.1 CVSS (Critical), it allows unauthenticated attackers to achieve high confidentiality and availability impacts via low-complexity network attacks. Despite its severity, there is no evidence of active exploitation, public exploit code, or significant community attention, and it is not present on the CISA KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.37CPE matchmatch criteria
cpe:2.3:a:toddr:yaml\:\:syck:*:*:*:*:*:perl:*:*
>= 0, <= 1.36CPE match
cpe:2.3:a:toddr:yaml\:\:syck:*:*:*:*:*:perl:*:*

CVSS Data

CVSS version used by this source: 3.1

9.1CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.43%
Probability of exploitation in next 30 days
EPSS Percentile
35.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0043 is in the 12th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

access.redhat.com / errata/RHSA-2026:6470
access.redhat.com / errata/RHSA-2026:8311
access.redhat.com / security/cve/CVE-2026-4177
bugzilla.redhat.com / show_bug.cgi
security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-4177.json
github.com / cpan-authors/YAML-Syck/commit/e8844a31c8cf0052914b198fc784ed4e6b8ae69e.patch
Patch
metacpan.org / release/TODDR/YAML-Syck-1.37_01/changes
Release Notes
openwall.com / lists/oss-security/2026/03/16/6
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