diff --git a/SOURCES/CVE-2021-33503.patch b/SOURCES/CVE-2021-33503.patch
new file mode 100644
index 0000000..80b1f1c
--- /dev/null
+++ b/SOURCES/CVE-2021-33503.patch
@@ -0,0 +1,61 @@
+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(-)
+
+diff --git a/src/urllib3/util/url.py b/src/urllib3/util/url.py
+index 6ff238fe3c..81a03da9e3 100644
+--- a/src/urllib3/util/url.py
++++ b/src/urllib3/util/url.py
+@@ -63,12 +63,12 @@
+ 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 == "":
+diff --git a/test/test_util.py b/test/test_util.py
+index a5b68a084b..88409e2d6c 100644
+--- a/test/test_util.py
++++ b/test/test_util.py
+@@ -438,6 +438,16 @@ def test_netloc(self, url, expected_netloc):
+                 fragment="hash",
+             ),
+         ),
++        # 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 --git a/SPECS/python-urllib3.spec b/SPECS/python-urllib3.spec
index 2ba969e..113eaf3 100644
--- a/SPECS/python-urllib3.spec
+++ b/SPECS/python-urllib3.spec
@@ -6,7 +6,7 @@
 
 Name:           python-%{srcname}
 Version:        1.25.10
-Release:        3%{?dist}
+Release:        4%{?dist}
 Summary:        Python HTTP library with thread-safe connection pooling and file post
 
 License:        MIT
@@ -14,6 +14,10 @@ URL:            https://github.com/urllib3/urllib3
 Source0:        %{url}/archive/%{version}/%{srcname}-%{version}.tar.gz
 # Unbundle ssl_match_hostname since we depend on it
 Source1:        ssl_match_hostname_py3.py
+# CVE-2021-33503 Catastrophic backtracking in URL authority parser
+# Tracking bug: https://bugzilla.redhat.com/show_bug.cgi?id=1968074
+# Upstream fix: https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec
+Patch0:         CVE-2021-33503.patch
 BuildArch:      noarch
 # Exclude i686 arch. Due to a modularity issue it's being added to the
 # x86_64 compose of CRB, but we don't want to ship it at all.
@@ -119,6 +123,10 @@ popd
 
 
 %changelog
+* Tue Jun 29 2021 Lumír Balhar <lbalhar@redhat.com> - 1.25.10-4
+- Fix for CVE-2021-33503 Catastrophic backtracking in URL authority parser
+Resolves: rhbz#1968074
+
 * Wed Jan 13 2021 Tomas Orsava <torsava@redhat.com> - 1.25.10-3
 - Convert from Fedora to the python39 module in RHEL8
 - Resolves: rhbz#1877430