From 00ae5cebf94cdddc04687f37f4b2c8846ca7d345 Mon Sep 17 00:00:00 2001
From: Jeffrey 'Alex' Clark <alex.clark@mongodb.com>
Date: Thu, 8 Oct 2026 13:51:15 -0400
Subject: [PATCH 1/3] PYTHON-6155 Prep 4.18.3 release

---
 doc/changelog.rst   | 16 ++++++++++++++++
 pymongo/_version.py |  2 +-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/doc/changelog.rst b/doc/changelog.rst
index 2a044aaccd..e8fb8a19b9 100644
--- a/doc/changelog.rst
+++ b/doc/changelog.rst
@@ -1,6 +1,22 @@
 Changelog
 =========
 
+Changes in Version 4.18.3 (2026/10/08)
+--------------------------------------
+
+Version 4.18.3 is a bug fix release.
+
+This release contains no user-facing changes. It fixes build and test
+infrastructure only.
+
+Issues Resolved
+...............
+
+See the `PyMongo 4.18.3 release notes in JIRA`_ for the list of resolved issues
+in this release.
+
+.. _PyMongo 4.18.3 release notes in JIRA: https://jira.mongodb.org/secure/ReleaseNote.jspa?projectId=10004&version=TODO
+
 Changes in Version 4.18.2 (2026/09/24)
 --------------------------------------
 
diff --git a/pymongo/_version.py b/pymongo/_version.py
index c988288efa..78a4b98d72 100644
--- a/pymongo/_version.py
+++ b/pymongo/_version.py
@@ -19,7 +19,7 @@
 import re
 from typing import Union
 
-__version__ = "4.18.3.dev0"
+__version__ = "4.18.3"
 
 
 def get_version_tuple(version: str) -> tuple[Union[int, str], ...]:

From 219e41fd08c5e8ba4190323ab16c8a4afaf03acb Mon Sep 17 00:00:00 2001
From: Jeffrey 'Alex' Clark <alex.clark@mongodb.com>
Date: Thu, 8 Oct 2026 13:55:31 -0400
Subject: [PATCH 2/3] PYTHON-6155 Add 4.18.3 Jira release notes link

---
 doc/changelog.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/changelog.rst b/doc/changelog.rst
index e8fb8a19b9..150fdde050 100644
--- a/doc/changelog.rst
+++ b/doc/changelog.rst
@@ -15,7 +15,7 @@ Issues Resolved
 See the `PyMongo 4.18.3 release notes in JIRA`_ for the list of resolved issues
 in this release.
 
-.. _PyMongo 4.18.3 release notes in JIRA: https://jira.mongodb.org/secure/ReleaseNote.jspa?projectId=10004&version=TODO
+.. _PyMongo 4.18.3 release notes in JIRA: https://jira.mongodb.org/secure/ReleaseNote.jspa?projectId=10004&version=52955
 
 Changes in Version 4.18.2 (2026/09/24)
 --------------------------------------

From 38a8604b13fe7fd02e8f039ccce33156312eb546 Mon Sep 17 00:00:00 2001
From: Jeffrey 'Alex' Clark <alex.clark@mongodb.com>
Date: Thu, 8 Oct 2026 14:39:20 -0400
Subject: [PATCH 3/3] PYTHON-6155 Add PYTHON-6110 to the 4.18.3 changelog

---
 doc/changelog.rst | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/doc/changelog.rst b/doc/changelog.rst
index 150fdde050..86b05d6ab8 100644
--- a/doc/changelog.rst
+++ b/doc/changelog.rst
@@ -6,8 +6,9 @@ Changes in Version 4.18.3 (2026/10/08)
 
 Version 4.18.3 is a bug fix release.
 
-This release contains no user-facing changes. It fixes build and test
-infrastructure only.
+- Hardened BSON regex decoding against malformed documents (`PYTHON-6110`_).
+
+.. _PYTHON-6110: https://jira.mongodb.org/browse/PYTHON-6110
 
 Issues Resolved
 ...............