CVE-2026-53550
MEDIUMDescription
js-yaml is a JavaScript YAML parser and dumper. Prior to 4.2.0 and 3.15.0, a crafted YAML document can trigger algorithmic CPU exhaustion in js-yaml merge-key processing (<<) by repeating the same alias many times in a merge sequence. This causes quadratic parse-time behavior relative to input size and can block a Node.js worker/event loop for seconds with a relatively small payload (tens of KB), resulting in denial of service. The issue is in merge handling inside lib/loader.js. This vulnerability is fixed in 4.2.0 and 3.15.0.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Exploit Intelligence
Low risk: more likely to be exploited than 31% of all known CVEs.
References
Related Vulnerabilities
Other CWE-407 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2020-27223 | Medium | 5.2 | 78% | - | Fix |
| CVE-2022-36021 | Medium | 5.5 | 60% | - | Fix |
| CVE-2021-33582 | High | 7.5 | 3.1% | - | Fix |
| CVE-2024-43485 | High | 7.5 | 3.1% | - | Fix |
| CVE-2024-43484 | High | 7.5 | 2.9% | - | Fix |
| CVE-2016-10396 | High | 7.5 | 2.9% | - | - |
Common questions
How do I fix CVE-2026-53550?
Published advisories record a fix for 5 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-53550 being actively exploited?
Not that we know of. CVE-2026-53550 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.38% is the estimated probability that it will be exploited in the next 30 days. That is higher than 31% of all scored CVEs.
How severe is CVE-2026-53550?
CVE-2026-53550 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-53550 affect?
Published advisories record a fix for node-js-yaml (Debian), nodejs24 (Red Hat / RHEL), nodejs24 (Rocky), nodejs26 (Rocky), and 1 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-09.