diff -Nru python-urllib3-1.25.8/debian/changelog python-urllib3-1.25.8/debian/changelog
--- python-urllib3-1.25.8/debian/changelog	2020-10-01 17:56:51.000000000 +0000
+++ python-urllib3-1.25.8/debian/changelog	2023-01-18 15:50:06.000000000 +0000
@@ -1,3 +1,13 @@
+python-urllib3 (1.25.8-2ubuntu0.2) focal-security; urgency=medium
+
+  * SECURITY UPDATE: DoS via URL regex backtracking
+    - debian/patches/CVE-2021-33503.patch: improve performance of
+      sub-authority splitting in URL in src/urllib3/util/url.py,
+      test/test_util.py.
+    - CVE-2021-33503
+
+ -- Marc Deslauriers <marc.deslauriers@ubuntu.com>  Wed, 18 Jan 2023 10:50:06 -0500
+
 python-urllib3 (1.25.8-2ubuntu0.1) focal-security; urgency=medium
 
   * SECURITY UPDATE: CRLF injection via method parameter
diff -Nru python-urllib3-1.25.8/debian/patches/CVE-2021-33503.patch python-urllib3-1.25.8/debian/patches/CVE-2021-33503.patch
--- python-urllib3-1.25.8/debian/patches/CVE-2021-33503.patch	1970-01-01 00:00:00.000000000 +0000
+++ python-urllib3-1.25.8/debian/patches/CVE-2021-33503.patch	2023-01-18 15:49:37.000000000 +0000
@@ -0,0 +1,57 @@
+From 2d4a3fee6de2fa45eb82169361918f759269b4ec Mon Sep 17 00:00:00 2001
+From: Seth Michael Larson <sethmichaellarson@gmail.com>
+Date: Wed, 26 May 2021 10:43:12 -0500
+Subject: [PATCH] Improve performance of sub-authority splitting in URL
+
+---
+ src/urllib3/util/url.py |  8 +++++---
+ test/test_util.py       | 10 ++++++++++
+ 2 files changed, 15 insertions(+), 3 deletions(-)
+
+--- a/src/urllib3/util/url.py
++++ b/src/urllib3/util/url.py
+@@ -63,12 +63,12 @@ IPV6_ADDRZ_RE = re.compile("^" + IPV6_AD
+ BRACELESS_IPV6_ADDRZ_RE = re.compile("^" + IPV6_ADDRZ_PAT[2:-2] + "$")
+ ZONE_ID_RE = re.compile("(" + ZONE_ID_PAT + r")\]$")
+ 
+-SUBAUTHORITY_PAT = (u"^(?:(.*)@)?(%s|%s|%s)(?::([0-9]{0,5}))?$") % (
++_HOST_PORT_PAT = ("^(%s|%s|%s)(?::([0-9]{0,5}))?$") % (
+     REG_NAME_PAT,
+     IPV4_PAT,
+     IPV6_ADDRZ_PAT,
+ )
+-SUBAUTHORITY_RE = re.compile(SUBAUTHORITY_PAT, re.UNICODE | re.DOTALL)
++_HOST_PORT_RE = re.compile(_HOST_PORT_PAT, re.UNICODE | re.DOTALL)
+ 
+ UNRESERVED_CHARS = set(
+     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789._-~"
+@@ -365,7 +365,9 @@ def parse_url(url):
+             scheme = scheme.lower()
+ 
+         if authority:
+-            auth, host, port = SUBAUTHORITY_RE.match(authority).groups()
++            auth, _, host_port = authority.rpartition("@")
++            auth = auth or None
++            host, port = _HOST_PORT_RE.match(host_port).groups()
+             if auth and normalize_uri:
+                 auth = _encode_invalid_chars(auth, USERINFO_CHARS)
+             if port == "":
+--- a/test/test_util.py
++++ b/test/test_util.py
+@@ -425,6 +425,16 @@ class TestUtil(object):
+                 query="%0D%0ASET%20test%20failure12%0D%0A:8080/test/?test=a",
+             ),
+         ),
++        # Tons of '@' causing backtracking
++        ("https://" + ("@" * 10000) + "[", False),
++        (
++            "https://user:" + ("@" * 10000) + "example.com",
++            Url(
++                scheme="https",
++                auth="user:" + ("%40" * 9999),
++                host="example.com",
++            ),
++        ),
+     ]
+ 
+     @pytest.mark.parametrize("url, expected_url", url_vulnerabilities)
diff -Nru python-urllib3-1.25.8/debian/patches/series python-urllib3-1.25.8/debian/patches/series
--- python-urllib3-1.25.8/debian/patches/series	2020-10-01 17:56:43.000000000 +0000
+++ python-urllib3-1.25.8/debian/patches/series	2023-01-18 15:49:33.000000000 +0000
@@ -2,3 +2,4 @@
 02_require-cert-verification.patch
 05_avoid-embedded-ssl-match-hostname.patch
 CVE-2020-26137.patch
+CVE-2021-33503.patch