diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-06-21-16-00-00.gh-issue-151773.mN4kRt.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-21-16-00-00.gh-issue-151773.mN4kRt.rst
new file mode 100644
index 00000000000000..b4193c5e15ffef
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-21-16-00-00.gh-issue-151773.mN4kRt.rst
@@ -0,0 +1,2 @@
+Fix a crash in :func:`contextvars.ContextVar.set` when memory allocation
+fails.
diff --git a/Python/context.c b/Python/context.c
index 0715612fbe79eb..9cec2eec189391 100644
--- a/Python/context.c
+++ b/Python/context.c
@@ -357,6 +357,9 @@ PyContextVar_Set(PyObject *ovar, PyObject *val)
     Py_XINCREF(old_val);
     PyContextToken *tok = token_new(ctx, var, old_val);
     Py_XDECREF(old_val);
+    if (tok == NULL) {
+        return NULL;
+    }
 
     if (contextvar_set(var, val)) {
         Py_DECREF(tok);