Showing 10 vulnerabilities on this page for js-yaml

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VulnerabilityTitle and contextCVSSEPSSPoCsSignalsSTIX action

js-yaml: Exponential parsing time in the flow collections leads to denial of service

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to k

CWE-407Aug 13, 2026
CVSS7.5v3.1EPSS-PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

JS-YAML: Quadratic CPU consumption in !!omap resolution (3.x and 4.x) — CVE-2026-59870 fix not backported

# Quadratic CPU consumption in `!!omap` resolution (js-yaml 3.x and 4.x) ## Summary `resolveYamlOmap()` enforces key uniqueness for `!!omap` sequences with a linear scan (`objectKeys.indexOf(...)`) inside the per-element loop, making resolution **O(n²)** in the number of entries. A modestly sized YAML document therefore consumes disproportionate CPU inside `yaml.load()`, giving a denial of service against any consumer that parses untrusted YAML. `!!omap` is registered in the **default schema*

CWE-407Aug 6, 2026
CVSS-v3.1EPSS-PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

js-yaml: YAML merge-key chains can force quadratic CPU consumption

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 5.2.0, when merge keys are enabled, js-yaml can spend quadratic CPU time parsing a document whose size grows only linearly when a chain of mappings uses merge keys where each mapping merges the previous one. This issue is fixed in version 5.2.0.

CVSS5.3v3.1EPSS0.41%PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

js-yaml: YAML merge-key chains can force quadratic CPU consumption

js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 before 3.15.0 and from 4.0.0 before 4.3.0, js-yaml can spend quadratic CPU time parsing a document whose size grows only linearly when a chain of mappings uses merge keys where each mapping merges the previous one. This issue is fixed in versions 3.15.0 and 4.3.0.

CWE-400CWE-407Jul 8, 2026
CVSS7.5v3.1EPSS0.423%PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

js-yaml quadratic-complexity denial of service via YAML11_SCHEMA !!omap parsing

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 5.2.1, YAML11_SCHEMA support for the !!omap tag in src/tag/sequence/omap.ts uses omapTag.addItem() to perform a linear duplicate-key scan on every insertion, causing O(n^2) CPU consumption when yaml.load() parses a crafted ordered-map document. This issue is fixed in version 5.2.1.

CWE-407CWE-770Jul 8, 2026
CVSS5.3v3.1EPSS0.41%PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

js-yaml: Quadratic-complexity DoS in merge key handling via repeated aliases

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 vulnerabil

CWE-407Jun 22, 2026
CVSS5.3v3.1EPSS0.378%PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

js-yaml has prototype pollution in merge (<<)

js-yaml is a JavaScript YAML parser and dumper. In js-yaml before 4.1.1 and 3.14.2, it's possible for an attacker to modify the prototype of the result of a parsed yaml document via prototype pollution (`__proto__`). All users who parse untrusted yaml documents may be impacted. The problem is patched in js-yaml 4.1.1 and 3.14.2. Users can protect against this kind of attack on the server by using `node --disable-proto=delete` or `deno` (in Deno, pollution protection is on by default).

CWE-1321Nov 13, 2025
CVSS5.3v3.1EPSS0.408%PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

Denial of Service in js-yaml

Versions of `js-yaml` prior to 3.13.0 are vulnerable to Denial of Service. By parsing a carefully-crafted YAML file, the node process stalls and may exhaust system resources leading to a Denial of Service. ## Recommendation Upgrade to version 3.13.0.

CWE-400Jun 5, 2019
CVSS-v3.1EPSS-PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

Code Injection in js-yaml

Versions of `js-yaml` prior to 3.13.1 are vulnerable to Code Injection. The `load()` function may execute arbitrary code injected through a malicious YAML file. Objects that have `toString` as key, JavaScript code as value and are used as explicit mapping keys allow attackers to execute the supplied code through the `load()` function. The `safeLoad()` function is unaffected. An example payload is `{ toString: !<tag:yaml.org,2002:js/function> 'function (){return Date.now()}' } : 1` which retur

CWE-94Jun 4, 2019
CVSS-EPSS-PoCs0SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX

Deserialization Code Execution in js-yaml

The JS-YAML module before 2.0.5 for Node.js parses input without properly considering the unsafe !!js/function tag, which allows remote attackers to execute arbitrary code via a crafted string that triggers an eval operation.

CWE-20Jun 28, 2013
CVSS6.8v2.0EPSS17.3%PoCs3SignalsNot listed in CISA KEVNo known ransomware useNo Nuclei templatesSTIX