Affected: docling-project docling, docling-project docling-slim

Docling simplifies document processing by parsing diverse formats and providing integrations with the generative AI ecosystem. From 2.0.0 until 2.131.0, the HTML, JATS, OpenDocument spreadsheet, and BoxNote backends, including docling/backend/html_backend.py, docling/backend/jats_backend.py, and docling/backend/boxnote_backend.py, accept the rowspan and colspan attribute values without an upper bound and execute loops or allocate a table grid proportional to the declared span. A very small document can therefore cause sustained CPU use or multi-gigabyte memory allocation, and the document_timeout setting does not interrupt the single backend conversion call. Export through the TableData.grid property can further materialize the oversized grid. This issue is fixed in 2.131.0.

Affected: PyPI: docling, PyPI: docling-slim

### Summary

The HTML, JATS, ODS (OpenDocument spreadsheet) and BoxNote backends accept table `rowspan` / `colspan` values without an upper bound. A few bytes of input, such as `<td rowspan="100000000">`, make docling run loops proportional to the declared span and allocate a table grid of the declared size. The result is CPU and memory exhaustion.

### Details

- `docling/backend/html_backend.py` (`_get_cell_spans`) parses span attributes with no upper limit. The cell-filling loop then iterates `row_span × col_span` times. - `docling/backend/jats_backend.py` and `docling/backend/boxnote_backend.py` fill their tables the same way. - The OpenDocument spreadsheet path scans the declared span range. - Export (for example `export_to_markdown()`) materialises the full grid through `TableData.grid` in docling-core.

`document_timeout` does not bound this. It is checked between pipeline stages, and these backends convert the whole document in a single call. `max_file_size` and `max_num_pages` do not help because the payload is tiny.

Measured on 2.130.0: a 54-byte HTML file with `rowspan="1e8"` takes about 4.4 s of CPU, and the time grows linearly with the value. A 52-byte file with `colspan="3000000"` takes about 23 s and reaches 4.5 GB peak memory during Markdown export.

### Impact

Denial of service of the converting process from a very small input document. Confidentiality and integrity are not affected.

### Proof of concept

```html <table><tr><td colspan="3000000">x</td></t…