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CVE-2026-4177

Toddr Yaml::syck buffer overflow

9.1 CRITICALEPSS 0.60%
  1. Published16 Mar 2026

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. 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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected products

Toddr Yaml::syck< 1.37

Remediation

Fixed in
Toddr Yaml::syck≥ 1.37

References

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Frequently asked

Is CVE-2026-4177 being actively exploited?

CVE-2026-4177 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.60%.

How severe is CVE-2026-4177?

CVE-2026-4177 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.60% probability of exploitation.

Which products are affected by CVE-2026-4177?

Affected products include Toddr Yaml::syck.

How do I fix CVE-2026-4177?

Upgrade affected software to a fixed version, for example Toddr Yaml::syck 1.37 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.