`annotation_layer.js` has logic to keep input elements in sync. The logic uses `document.getElementsByName` with [a name derived from the PDF](https://github.com/mozilla/pdf.js/blob/10a1db698047e612e8ae3da66d12a6c1ac5597a3/src/core/annotation.js#L407) to retrieve the set of related elements. This query is not namespaced, so if the viewer ever adds a `name` attribute to a checkbox or radio input in the page, then the PDF file can get it changed (without user interaction via the scripting interface). Fortunately, there doesn't appear to be any input/radio element in the default viewer code. A custom viewer can be affected by this bug, however.

I suggest to replace the `document.getElementsByTagName` calls with a function that checks that the elements are created by the `annotation_layer.js` code before returning them. There are several ways to do so, e.g. by adding a custom attribute to each input element.

## Seemingly generic property assignment
This code on its own looks dangerous because it allows the caller to overwrite any property
https://github.com/mozilla/pdf.js/blob/99e442941c16561e8826a925b164d79f4ad51fbf/src/display/annotation_layer.js#L684-L688
Fortunately, it is only called with a fixed key, so only the `value` property can be updated in response to user input events:
https://github.com/mozilla/pdf.js/blob/99e442941c16561e8826a925b164d79f4ad51fbf/src/display/annotation_layer.js#L732-L740

## Unchecking other checkboxes on checkbox state change
https://github.com/mozilla/pdf.js/blob/99e442941c16561e8826a925b164d79f4ad51fbf/src/display/annotation_layer.js#L979-L990

## Updating the abstract state (storage)
https://github.com/mozilla/pdf.js/blob/99e442941c16561e8826a925b164d79f4ad51fbf/src/display/annotation_layer.js#L1061-L1065

## Allowing scripts to uncheck checkbox/radio inputs
The others require user interaction to have any effect; this one allows scripts embedded in the PDF to run logic without user interaction.
https://github.com/mozilla/pdf.js/blob/99e442941c16561e8826a925b164d79f4ad51fbf/src/display/annotation_layer.js#L1073-L1077
* @property {string} dir - Text direction: 'ttb', 'ltr' or 'rtl'.
 * @property {Array<any>} transform - Transformation matrix.
 * @property {number} width - Width in device space.
 * @property {number} height - Height in device space.
 * @property {string} fontName - Font name used by PDF.js for converted font.
 * @property {boolean} hasEOL - Indicating if the text content is followed by a
 *   line-break.
 */
/**
 * Page text marked content part.
 *
 * @typedef {Object} TextMarkedContent
 * @property {string} type - Either 'beginMarkedContent',
 *   'beginMarkedContentProps', or 'endMarkedContent'.
 * @property {string} id - The marked content identifier. Only used for type
 *   'beginMarkedContentProps'.
 */
/**
 * Text style.
 *
 * @typedef {Object} TextStyle
 * @property {number} ascent - Font ascent.
 * @property {number} descent - Font descent.
 * @property {boolean} vertical - Whether or not the text is in vertical mode.
 * @property {string} fontFamily - The possible font family.
 */
/**
 * Page annotation parameters.
 *
 * @typedef {Object} GetAnnotationsParameters