[GHSA-h67p-54hq-rp68] JS-YAML: Quadratic-complexity DoS in merge key handling via repeated aliases

[mazze93]

Updates

• CVSS v3
• CWEs
• Description
• References
• Severity

Comments
While deduplicating repeated merge aliases by reference removes redundant work for identical sources, an attacker can still construct long merge chains using distinct anchors that resolve to different but structurally equivalent mappings.
Each such mapping incurs a full merge, so the total work remains near-quadratic in the number of keys and merge sources, even though the final merged object does not benefit from the redundancy.

[github]

Hi there @puzrin! A community member has suggested an improvement to your security advisory. If approved, this change will affect the global advisory listed at github.com/advisories. It will not affect the version listed in your project repository.

This change will be reviewed by our Security Curation Team. If you have thoughts or feedback, please share them in a comment here! If this PR has already been closed, you can start a new community contribution for this advisory

[puzrin]

Please create a new security report with a POC showing poor timing for realistic input sizes. I see no reason to edit the old ones about a different pattern.

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