CVE-2026-73643

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 keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2.

Database specific

{
    "cna_assigner": "GitHub_M",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73643.json",
    "cwe_ids": [
        "CWE-407"
    ]
}

References

Affected packages

Git / github.com/nodeca/js-yaml

Affected ranges

Type

GIT

Repo

https://github.com/nodeca/js-yaml

Events

Introduced

75148bc4f5eb69b3d338e1c355d8bb2dba5bdf34

Fixed

3e5240f9cbe645ce5afb58524954a13c8539c853

Database specific

Show details

{
    "extracted_events": [
        {
            "introduced": "5.0.0"
        },
        {
            "fixed": "5.2.2"
        }
    ],
    "source": [
        "AFFECTED_FIELD",
        "REFERENCES"
    ]
}

Affected versions

5.*

5.0.0

5.1.0

5.2.0

5.2.1

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73643.json"