diff --git a/pyproject.toml b/pyproject.toml
index 627d29142..b94a1ced6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -84,7 +84,7 @@ dev = [
     "sphinx-copybutton==0.5.2",
     "sphinx-lint==1.0.2",
     "sphinx-pyproject==0.3.0",
-    "sphinx-substitution-extensions==2026.8.13.1",
+    "sphinx-substitution-extensions==2026.10.9",
     "sphinxcontrib-spelling==8.0.2",
     # ``sphinxcontrib-towncrier`` renders unreleased news fragments
     # as Markdown in docs/source/unreleased.md during Sphinx builds.