AIKIDO-2026-641142
js-yaml is vulnerable to Denial of Service (DoS)
75
High Risk
This Affects:
js-yamlTL;DR
Affected versions of this package are vulnerable to Denial of Service (DoS) because the maxTotalMergeKeys safeguard does not count empty mappings during merge processing. A crafted YAML document that repeatedly merges a large sequence of empty mappings generates work while the merge-key counter stays unchanged, bypassing the configured protection. Parsing such a document consumes significant CPU and can make the application unavailable. The fix counts each merge-source mapping as a budget unit in addition to counting its keys.
Who does this affect?
You are affected if your application uses an affected version to parse untrusted YAML input.
Background info
js-yaml is vulnerable to Denial of Service (DoS) in versions 3.0.0 - 3.15.1 and 4.0.0 - 4.3.1.
How to fix this
Upgrade the js-yaml library to the patch version.
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