diff --git a/graphify/export.py b/graphify/export.py
index d363aa3c..d7a7349a 100644
--- a/graphify/export.py
+++ b/graphify/export.py
@@ -365,7 +365,7 @@ def to_html(
     legend_data = []
     for cid in sorted((community_labels or {}).keys()):
         color = COMMUNITY_COLORS[cid % len(COMMUNITY_COLORS)]
-        lbl = (community_labels or {}).get(cid, f"Community {cid}")
+        lbl = _html.escape(sanitize_label((community_labels or {}).get(cid, f"Community {cid}")))
         n = len(communities.get(cid, []))
         legend_data.append({"cid": cid, "color": color, "label": lbl, "count": n})
 
diff --git a/graphify/hooks.py b/graphify/hooks.py
index 51959ffb..f2c74e3c 100644
--- a/graphify/hooks.py
+++ b/graphify/hooks.py
@@ -17,6 +17,11 @@ if [ -n "$GRAPHIFY_BIN" ]; then
         */env\\ *) GRAPHIFY_PYTHON="${_SHEBANG#*/env }" ;;
         *)         GRAPHIFY_PYTHON="$_SHEBANG" ;;
     esac
+    # Allowlist: only keep characters valid in a filesystem path to prevent
+    # injection if the shebang contains shell metacharacters
+    case "$GRAPHIFY_PYTHON" in
+        *[!a-zA-Z0-9/_.-]*) GRAPHIFY_PYTHON="python3" ;;
+    esac
     if ! "$GRAPHIFY_PYTHON" -c "import graphify" 2>/dev/null; then
         GRAPHIFY_PYTHON="python3"
     fi