diff -r a70ca6f35327 Lib/test/test_io.py
--- a/Lib/test/test_io.py	Mon Mar 30 11:48:50 2015 -0400
+++ b/Lib/test/test_io.py	Wed Apr 01 13:48:32 2015 -0400
@@ -1179,6 +1179,14 @@
             self.assertEqual(rawio._extraneous_reads, 0,
                              "failed for {}: {} != 0".format(n, rawio._extraneous_reads))
 
+    def test_read_on_closed(self):
+        # Issue #23796
+        b = io.BufferedReader(io.BytesIO(b"12"))
+        b.read(1)
+        b.close()
+        self.assertRaises(ValueError, b.peek)
+        self.assertRaises(ValueError, b.read1, 1)
+
 
 class CBufferedReaderTest(BufferedReaderTest, SizeofTest):
     tp = io.BufferedReader
diff -r a70ca6f35327 Modules/_io/bufferedio.c
--- a/Modules/_io/bufferedio.c	Mon Mar 30 11:48:50 2015 -0400
+++ b/Modules/_io/bufferedio.c	Wed Apr 01 13:48:32 2015 -0400
@@ -882,6 +882,7 @@
     PyObject *res = NULL;
 
     CHECK_INITIALIZED(self)
+    CHECK_CLOSED(self, "peek of closed file")
     if (!PyArg_ParseTuple(args, "|n:peek", &n)) {
         return NULL;
     }
@@ -956,6 +957,9 @@
                         "read length must be positive");
         return NULL;
     }
+
+    CHECK_CLOSED(self, "read of closed file")
+
     if (n == 0)
         return PyBytes_FromStringAndSize(NULL, 0);