add pymdownx snippets config override

README.md

@@ -146,6 +146,9 @@ We only use `material-mkdocs` as base styles because Backstage also uses the `Ma
 
 ### Unreleased
 
+### 1.2.2
+ - Added config override of `pymdownx.snippets` for [security](https://github.com/facelessuser/pymdown-extensions/security/advisories/GHSA-jh85-wwv9-24hv). `restrict_base_path` will always be `true`. If you currently use snippets with files outside of the directory, those files will no longer be included. 
+
 ### 1.2.1
  - Use latest version of `pymdown-extensions` which contains [security fixes](https://github.com/backstage/mkdocs-techdocs-core/pull/123).
 

setup.py

@@ -27,7 +27,7 @@
 
 setup(
     name="mkdocs-techdocs-core",
-    version="1.2.1",
+    version="1.2.2",
     description="The core MkDocs plugin used by Backstage's TechDocs as a wrapper around "
     "multiple MkDocs plugins and Python Markdown extensions",
     long_description=long_description,

src/core.py

@@ -50,6 +50,11 @@ def on_config(self, config):
         if "mdx_configs" in config:
             mdx_configs_override = config["mdx_configs"].copy()
 
+        # Pymdown snippets override to prevent legacy behavior impacting security https://github.com/facelessuser/pymdown-extensions/security/advisories/GHSA-jh85-wwv9-24hv
+        mdx_configs_override["pymdownx.snippets"] = {
+            "restrict_base_path": True,
+        }
+
         # Theme
         if config["theme"].name != TECHDOCS_DEFAULT_THEME:
             config["theme"] = Theme(name=TECHDOCS_DEFAULT_THEME)
@@ -103,6 +108,7 @@ def on_config(self, config):
         config["markdown_extensions"].append("pymdownx.magiclink")
         config["markdown_extensions"].append("pymdownx.mark")
         config["markdown_extensions"].append("pymdownx.smartsymbols")
+        config["markdown_extensions"].append("pymdownx.snippets")
         config["markdown_extensions"].append("pymdownx.superfences")
         config["markdown_extensions"].append("pymdownx.highlight")
         config["mdx_configs"]["pymdownx.highlight"] = {

src/test_core.py

@@ -99,3 +99,15 @@ def test_template_renders__multiline_value_as_valid_json(self):
         rendered = template.render(config=config)
         as_json = json.loads(rendered)
         self.assertEquals(config, as_json)
+
+    def test_restrict_snippet_base_path(self):
+        self.mkdocs_yaml_config["mdx_configs"] = {
+            "pymdownx.snippets": {"restrict_base_path": False}
+        }
+
+        final_config = self.techdocscore.on_config(self.mkdocs_yaml_config)
+
+        self.assertEqual(
+            final_config["mdx_configs"]["pymdownx.snippets"]["restrict_base_path"],
+            True,
+        )