Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HSummary
CVE-2026-4177 is a critical-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Toddr Yaml\. Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 36th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-4177 affects YAML::Syck versions through 1.36, a Perl module for parsing and emitting YAML data. The vulnerability encompasses multiple issues, with a high-severity heap buffer overflow in the YAML emitter triggered when class names exceed the initial 512-byte allocation. Additional flaws include a base64 decoder reading past the buffer end on trailing newlines, strtok mutating n->type_id in place and corrupting shared node data, and a memory leak in syck_hdlr_add_anchor when a node already has an anchor, leaking the incoming anchor string on early return. These are classified under CWE-122 (Heap-based Buffer Overflow) with a CVSS v3.1 base score of 9.1.
Remote attackers require no privileges or user interaction to exploit this over the network with low complexity. Successful exploitation of the heap buffer overflow can lead to high confidentiality and availability impacts, potentially allowing arbitrary code execution, sensitive data disclosure, or denial of service through memory corruption or crashes.
Patches addressing these issues appear in YAML::Syck version 1.37_01, as detailed in the release changes on MetaCPAN, and a specific GitHub commit provides the fix. An announcement on the oss-security mailing list from March 16, 2026, discloses the vulnerabilities and references these mitigations.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-12523
Vulnerability Data
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…
more
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.2.1V1.4.1
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and memory-error detectors) can discover heap overflows after they have been coded.
Input validation enforces bounds checking on data written to heap buffers, directly stopping the overflow condition from being introduced.
Security engineering principles require use of memory-safe constructs and bounds-checked allocation routines that avoid introducing heap overflows.
Memory-protection mechanisms limit the ability of a heap overflow to execute attacker-controlled code or corrupt adjacent structures.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.
Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.
Timely patching removes known heap-overflow instances after they exist.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure coding directly requires bounds-checked memory operations, addressing the root cause of CWE-120.
Security testing in development and acceptance can detect heap overflows before release.
Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.
Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.
Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.
Change management ensures controlled deployment of fixes for discovered heap-overflow vulnerabilities.