CVE-2026-126066

### Summary With the non-default stopNodes option, a stop node's body with many "<a " fragments and no closing ">" anywhere after makes readStopNodeData() rescan the entire remaining input from every "<". The failed lookahead is neither cached nor bounded, so n fragments cost O(n²) before the parser throws. Availability-only (CPU exhaustion), needs the non-default stopNodes option — not benchmarked yet, see Proof of Concept. ### Details **CWE-407** — Inefficient Algorithmic Complexity **Code** - `OrderedObjParser.js:520` — `parseXml()` calls `readStopNodeData()` after a matching stop node opens - `OrderedObjParser.js:810` — calls `readTagExp()` for every non-special `<` - `OrderedObjParser.js:688-722` — `tagExpWithClosingIndex()` scans to end-of-input and returns `undefined` when no `>` exists - `OrderedObjParser.js:812-818` — on failure, `i` isn't advanced, so the next `<` repeats the same full scan - `OrderedObjParser.js:423` — the main parse loop throws immediately on the same failure; only the stop-node path retries **Root cause:** a failed closing-`>` lookahead is neither cached nor bounded — `n` copies of `<a ` with no later `>` means `n` scans over the remaining input, O(n²) work, before it finally throws. **Fix** 1. Throw immediately in `readStopNodeData()` when `readTagExp()` returns `undefined` 2. Or break the loop on the first failed scan 3. Or find the next `>` once and reuse/bound that result 4. Add a test asserting near-linear scaling when payload size doubles ### Proof of concept Not benchmarked — static-analysis finding, confidence 0.5. To confirm: configure `stopNodes` matching a root element. Build input as `'<stop>' + '<a '.repeat(n)`. Time `parse()` until it throws `Unexpected end of <tag>`. Start around n=10,000 and double it — quadratic should show ~4x time per doubling, linear ~2x. Control: same input with a `>` present, or `stopNodes` unset. ### Impact CPU-exhaustion DoS in Node.js services parsing untrusted XML with `stopNodes` en