Bump version to 6.4.2

Author: bdarnell

Diff for: docs/releases.rst

@@ -4,6 +4,7 @@ Release notes
 .. toctree::
    :maxdepth: 2
 
+   releases/v6.4.2
    releases/v6.4.1
    releases/v6.4.0
    releases/v6.3.3

Diff for: docs/releases/v6.4.2.rst

@@ -0,0 +1,12 @@
+What's new in Tornado 6.4.2
+===========================
+
+Nov 21, 2024
+------------
+
+Security Improvements
+~~~~~~~~~~~~~~~~~~~~~
+
+- Parsing of the cookie header is now much more efficient. The older algorithm sometimes had
+  quadratic performance which allowed for a denial-of-service attack in which the server would spend
+  excessive CPU time parsing cookies and block the event loop. This change fixes CVE-2024-7592.

Diff for: tornado/__init__.py

@@ -22,8 +22,8 @@
 # is zero for an official release, positive for a development branch,
 # or negative for a release candidate or beta (after the base version
 # number has been incremented)
-version = "6.4.1"
-version_info = (6, 4, 0, 1)
+version = "6.4.2"
+version_info = (6, 4, 2, 0)
 
 import importlib
 import typing