[GHSA] GHSA-8344-3jmq-59r6 (high) — xmldom: Quadratic-time attribute deduplication

GHSA-8344-3jmq-59r6 Severity: high CVE: CVE-2026-83613

xmldom: Quadratic-time attribute deduplication

## Summary

xmldom builds the attribute collection of every parsed element by inserting attributes one at a time into a DOM `NamedNodeMap`. Each insertion first performs a **linear scan of all already-inserted attributes** to enforce the DOM uniqueness rule (no two attributes with the same quali