Add SRI (Subresource Integrity) hash to CDN script tags

CHANGELOG.md

@@ -8,6 +8,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Add support for Kaleido>=v1.0.0 for image generation, and deprecate support for Kaleido<1 and Orca [[#5062](https://github.com/plotly/plotly.py/pull/5062)]
 - Reduce package bundle size by 18-24% via changes to code generation [[#4978](https://github.com/plotly/plotly.py/pull/4978)]
 
+### Added
+- Add SRI (Subresource Integrity) hash support for CDN script tags when using `include_plotlyjs='cdn'`. This enhances security by ensuring browser verification of CDN-served plotly.js files [[#PENDING](https://github.com/plotly/plotly.py/pull/PENDING)]
+
 ### Fixed
 - Fix third-party widget display issues in v6 [[#5102](https://github.com/plotly/plotly.py/pull/5102)]
 - Add handling for case where `jupyterlab` or `notebook` is not installed [[#5104](https://github.com/plotly/plotly.py/pull/5104/files)]

plotly/io/_html.py

@@ -1,6 +1,8 @@
 import uuid
 from pathlib import Path
 import webbrowser
+import hashlib
+import base64
 
 from _plotly_utils.optional_imports import get_module
 from plotly.io._utils import validate_coerce_fig_to_dict, plotly_cdn_url
@@ -9,6 +11,14 @@
 _json = get_module("json")
 
 
+def _generate_sri_hash(content):
+    """Generate SHA256 hash for SRI (Subresource Integrity)"""
+    if isinstance(content, str):
+        content = content.encode("utf-8")
+    sha256_hash = hashlib.sha256(content).digest()
+    return "sha256-" + base64.b64encode(sha256_hash).decode("utf-8")
+
+
 # Build script to set global PlotlyConfig object. This must execute before
 # plotly.js is loaded.
 _window_plotly_config = """\
@@ -252,11 +262,17 @@ def to_html(
     load_plotlyjs = ""
 
     if include_plotlyjs == "cdn":
+        # Generate SRI hash from the bundled plotly.js content
+        plotlyjs_content = get_plotlyjs()
+        sri_hash = _generate_sri_hash(plotlyjs_content)
+
         load_plotlyjs = """\
         {win_config}
-        <script charset="utf-8" src="{cdn_url}"></script>\
+        <script charset="utf-8" src="{cdn_url}" integrity="{integrity}" crossorigin="anonymous"></script>\
     """.format(
-            win_config=_window_plotly_config, cdn_url=plotly_cdn_url()
+            win_config=_window_plotly_config,
+            cdn_url=plotly_cdn_url(),
+            integrity=sri_hash,
         )
 
     elif include_plotlyjs == "directory":

tests/test_core/test_offline/test_offline.py

@@ -37,9 +37,7 @@
 <script type="text/javascript">\
 window.PlotlyConfig = {MathJaxConfig: 'local'};</script>"""
 
-cdn_script = '<script charset="utf-8" src="{cdn_url}"></script>'.format(
-    cdn_url=plotly_cdn_url()
-)
+cdn_script = '<script charset="utf-8" src="{cdn_url}"'.format(cdn_url=plotly_cdn_url())
 
 directory_script = '<script charset="utf-8" src="plotly.min.js"></script>'
 

tests/test_io/test_html.py

@@ -7,6 +7,8 @@
 import plotly.graph_objs as go
 import plotly.io as pio
 from plotly.io._utils import plotly_cdn_url
+from plotly.offline.offline import get_plotlyjs
+from plotly.io._html import _generate_sri_hash
 
 
 if sys.version_info >= (3, 3):
@@ -46,3 +48,45 @@ def test_html_deterministic(fig1):
     assert pio.to_html(fig1, include_plotlyjs="cdn", div_id=div_id) == pio.to_html(
         fig1, include_plotlyjs="cdn", div_id=div_id
     )
+
+
+def test_cdn_includes_integrity_attribute(fig1):
+    """Test that the CDN script tag includes an integrity attribute with SHA256 hash"""
+    html_output = pio.to_html(fig1, include_plotlyjs="cdn")
+
+    # Check that the script tag includes integrity attribute
+    assert 'integrity="sha256-' in html_output
+    assert 'crossorigin="anonymous"' in html_output
+
+    # Verify it's in the correct script tag
+    import re
+
+    cdn_pattern = re.compile(
+        r'<script[^>]*src="'
+        + re.escape(plotly_cdn_url())
+        + r'"[^>]*integrity="sha256-[A-Za-z0-9+/=]+"[^>]*>'
+    )
+    match = cdn_pattern.search(html_output)
+    assert match is not None, "CDN script tag with integrity attribute not found"
+
+
+def test_cdn_integrity_hash_matches_bundled_content(fig1):
+    """Test that the SRI hash in CDN script tag matches the bundled plotly.js content"""
+    html_output = pio.to_html(fig1, include_plotlyjs="cdn")
+
+    # Extract the integrity hash from the HTML output
+    import re
+
+    integrity_pattern = re.compile(r'integrity="(sha256-[A-Za-z0-9+/=]+)"')
+    match = integrity_pattern.search(html_output)
+    assert match is not None, "Integrity attribute not found"
+    extracted_hash = match.group(1)
+
+    # Generate expected hash from bundled content
+    plotlyjs_content = get_plotlyjs()
+    expected_hash = _generate_sri_hash(plotlyjs_content)
+
+    # Verify they match
+    assert (
+        extracted_hash == expected_hash
+    ), f"Hash mismatch: expected {expected_hash}, got {extracted_hash}"

tests/test_io/test_renderers.py

@@ -303,7 +303,7 @@ def test_repr_html(renderer):
         "window.PlotlyConfig = {MathJaxConfig: 'local'};</script>\n        "
         '<script charset="utf-8" src="'
         + plotly_cdn_url()
-        + '"></script>                '
+        + '" integrity="sha256-oy6Be7Eh6eiQFs5M7oXuPxxm9qbJXEtTpfSI93dW16Q=" crossorigin="anonymous"></script>                '
         '<div id="cd462b94-79ce-42a2-887f-2650a761a144" class="plotly-graph-div" '
         'style="height:100%; width:100%;"></div>            <script type="text/javascript">'
         "                window.PLOTLYENV=window.PLOTLYENV || {};"