diff --git a/SOURCES/CVE-2021-43818.patch b/SOURCES/CVE-2021-43818.patch
new file mode 100644
index 0000000..7413abc
--- /dev/null
+++ b/SOURCES/CVE-2021-43818.patch
@@ -0,0 +1,127 @@
+diff --git a/src/lxml/html/clean.py b/src/lxml/html/clean.py
+index 6f3f7de..da5af16 100644
+--- a/src/lxml/html/clean.py
++++ b/src/lxml/html/clean.py
+@@ -73,18 +73,25 @@ _looks_like_tag_content = re.compile(
+ 
+ # All kinds of schemes besides just javascript: that can cause
+ # execution:
+-_is_image_dataurl = re.compile(
+-    r'^data:image/.+;base64', re.I).search
++_find_image_dataurls = re.compile(
++    r'^data:image/(.+);base64,', re.I).findall
+ _is_possibly_malicious_scheme = re.compile(
+-    r'(?:javascript|jscript|livescript|vbscript|data|about|mocha):',
+-    re.I).search
++    r'(javascript|jscript|livescript|vbscript|data|about|mocha):',
++    re.I).findall
++# SVG images can contain script content
++_is_unsafe_image_type = re.compile(r"(xml|svg)", re.I).findall
++
+ def _is_javascript_scheme(s):
+-    if _is_image_dataurl(s):
+-        return None
+-    return _is_possibly_malicious_scheme(s)
++    is_image_url = False
++    for image_type in _find_image_dataurls(s):
++        is_image_url = True
++        if _is_unsafe_image_type(image_type):
++            return True
++    if is_image_url:
++        return False
++    return bool(_is_possibly_malicious_scheme(s))
+ 
+ _substitute_whitespace = re.compile(r'[\s\x00-\x08\x0B\x0C\x0E-\x19]+').sub
+-# FIXME: should data: be blocked?
+ 
+ # FIXME: check against: http://msdn2.microsoft.com/en-us/library/ms537512.aspx
+ _conditional_comment_re = re.compile(
+@@ -512,6 +519,8 @@ class Cleaner(object):
+             return True
+         if 'expression(' in style:
+             return True
++        if '@import' in style:
++            return True
+         if '</noscript' in style:
+             # e.g. '<noscript><style><a title="</noscript><img src=x onerror=alert(1)>">'
+             return True
+diff --git a/src/lxml/html/tests/test_clean.py b/src/lxml/html/tests/test_clean.py
+index e40cdad..ad9a598 100644
+--- a/src/lxml/html/tests/test_clean.py
++++ b/src/lxml/html/tests/test_clean.py
+@@ -1,3 +1,5 @@
++import base64
++import gzip
+ import unittest, sys
+ from lxml.tests.common_imports import make_doctest
+ from lxml.etree import LIBXML_VERSION
+@@ -89,6 +91,69 @@ class CleanerTest(unittest.TestCase):
+             b'<math><style>/* deleted */</style></math>',
+             lxml.html.tostring(clean_html(s)))
+ 
++    def test_sneaky_import_in_style(self):
++        # Prevent "@@importimport" -> "@import" replacement.
++        style_codes = [
++            "@@importimport(extstyle.css)",
++            "@ @  import import(extstyle.css)",
++            "@ @ importimport(extstyle.css)",
++            "@@  import import(extstyle.css)",
++            "@ @import import(extstyle.css)",
++            "@@importimport()",
++        ]
++        for style_code in style_codes:
++            html = '<style>%s</style>' % style_code
++            s = lxml.html.fragment_fromstring(html)
++
++            cleaned = lxml.html.tostring(clean_html(s))
++            self.assertEqual(
++                b'<style>/* deleted */</style>',
++                cleaned,
++                "%s  ->  %s" % (style_code, cleaned))
++
++    def test_svg_data_links(self):
++        # Remove SVG images with potentially insecure content.
++        svg = b'<svg onload="alert(123)" />'
++        svgz = gzip.compress(svg)
++        svg_b64 = base64.b64encode(svg).decode('ASCII')
++        svgz_b64 = base64.b64encode(svgz).decode('ASCII')
++        urls = [
++            "data:image/svg+xml;base64," + svg_b64,
++            "data:image/svg+xml-compressed;base64," + svgz_b64,
++        ]
++        for url in urls:
++            html = '<img src="%s">' % url
++            s = lxml.html.fragment_fromstring(html)
++
++            cleaned = lxml.html.tostring(clean_html(s))
++            self.assertEqual(
++                b'<img src="">',
++                cleaned,
++                "%s  ->  %s" % (url, cleaned))
++
++    def test_image_data_links(self):
++        data = b'123'
++        data_b64 = base64.b64encode(data).decode('ASCII')
++        urls = [
++            "data:image/jpeg;base64," + data_b64,
++            "data:image/apng;base64," + data_b64,
++            "data:image/png;base64," + data_b64,
++            "data:image/gif;base64," + data_b64,
++            "data:image/webp;base64," + data_b64,
++            "data:image/bmp;base64," + data_b64,
++            "data:image/tiff;base64," + data_b64,
++            "data:image/x-icon;base64," + data_b64,
++        ]
++        for url in urls:
++            html = '<img src="%s">' % url
++            s = lxml.html.fragment_fromstring(html)
++
++            cleaned = lxml.html.tostring(clean_html(s))
++            self.assertEqual(
++                html.encode("UTF-8"),
++                cleaned,
++                "%s  ->  %s" % (url, cleaned))
++
+     def test_formaction_attribute_in_button_input(self):
+         # The formaction attribute overrides the form's action and should be
+         # treated as a malicious link attribute
diff --git a/SOURCES/fix-threading-tests.patch b/SOURCES/fix-threading-tests.patch
new file mode 100644
index 0000000..27a5052
--- /dev/null
+++ b/SOURCES/fix-threading-tests.patch
@@ -0,0 +1,26 @@
+diff --git a/src/lxml/tests/test_threading.py b/src/lxml/tests/test_threading.py
+index 8948c3e..5ede3f8 100644
+--- a/src/lxml/tests/test_threading.py
++++ b/src/lxml/tests/test_threading.py
+@@ -130,7 +130,7 @@ class ThreadingTestCase(HelperTestCase):
+     <xsl:template match="tag" />
+     <!-- extend time for parsing + transform -->
+ ''' + '\n'.join('<xsl:template match="tag%x" />' % i for i in range(200)) + '''
+-    <xsl:foo />
++    <xsl:UnExpectedElement />
+ </xsl:stylesheet>''')
+         self.assertRaises(etree.XSLTParseError,
+                           etree.XSLT, style)
+@@ -153,9 +153,10 @@ class ThreadingTestCase(HelperTestCase):
+             self.assertTrue(len(log))
+             if last_log is not None:
+                 self.assertEqual(len(last_log), len(log))
+-            self.assertEqual(4, len(log))
++            self.assertTrue(len(log) >= 2, len(log))
+             for error in log:
+-                self.assertTrue(':ERROR:XSLT:' in str(error))
++                self.assertTrue(':ERROR:XSLT:' in str(error), str(error))
++            self.assertTrue(any('UnExpectedElement' in str(error) for error in log), log)
+             last_log = log
+ 
+     def test_thread_xslt_apply_error_log(self):
diff --git a/SPECS/python-lxml.spec b/SPECS/python-lxml.spec
index cc5da76..3247621 100644
--- a/SPECS/python-lxml.spec
+++ b/SPECS/python-lxml.spec
@@ -1,15 +1,8 @@
-%if 0%{?rhel} > 7
-# Disable python2 build by default
-%bcond_with python2
-%else
-%bcond_without python2
-%endif
-
 %global modname lxml
 
 Name:           python-%{modname}
 Version:        4.2.3
-Release:        3%{?dist}
+Release:        4%{?dist}
 Summary:        XML processing library combining libxml2/libxslt with the ElementTree API
 
 License:        BSD
@@ -28,6 +21,17 @@ Patch0:         CVE-2020-27783.patch
 # Fixed upstream: https://github.com/lxml/lxml/commit/2d01a1ba8984e0483ce6619b972832377f208a0d
 Patch1: CVE-2021-28957.patch
 
+# Fix for CVE-2021-43818: HTML Cleaner allows crafted
+# and SVG embedded scripts to pass through
+# Fixed upstream:
+# https://github.com/lxml/lxml/commit/12fa9669007180a7bb87d990c375cf91ca5b664a
+# https://github.com/lxml/lxml/commit/f2330237440df7e8f39c3ad1b1aa8852be3b27c0
+Patch2: CVE-2021-43818.patch
+
+# Make test more resilient against changes in latest libxslt releases
+# Fixed upstream: https://github.com/lxml/lxml/commit/acef361ca80ff9afd828d91c98ea91c92f9d09af
+Patch3: fix-threading-tests.patch
+
 BuildRequires:  gcc
 BuildRequires:  libxml2-devel
 BuildRequires:  libxslt-devel
@@ -41,22 +45,6 @@ home page < or see our bug tracker at case you want to use the current ...
 
 %description %{_description}
 
-%if %{with python2}
-%package -n     python2-%{modname}
-Summary:        %{summary}
-BuildRequires:  python2-devel
-BuildRequires:  python2-setuptools
-BuildRequires:  python2-Cython
-Recommends:     python2-cssselect
-Recommends:     python2-html5lib
-Recommends:     python2-beautifulsoup4
-%{?python_provide:%python_provide python2-%{modname}}
-
-%description -n python2-%{modname} %{_description}
-
-Python 2 version.
-%endif # with python2
-
 %package -n     python3-%{modname}
 Summary:        %{summary}
 BuildRequires:  python3-devel
@@ -76,30 +64,17 @@ Python 3 version.
 
 %build
 export WITH_CYTHON=true
-%if %{with python2}
-%py2_build
-%endif # with python2
 %py3_build
 
 %install
-%if %{with python2}
-%py2_install
-%endif # with python2
 %py3_install
 
 %check
-%if %{with python2}
-%{__python2} setup.py test
-%endif # with python2
-%{__python3} setup.py test
-
-%if %{with python2}
-%files -n python2-%{modname}
-%license doc/licenses/ZopePublicLicense.txt LICENSES.txt
-%doc README.rst src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/readme.txt
-%{python2_sitearch}/%{modname}/
-%{python2_sitearch}/%{modname}-*.egg-info/
-%endif # with python2
+# The tests assume inplace build, so we copy the built library to source-dir.
+# If not done that, Python can either import the tests or the extension modules, but not both.
+cp -a build/lib.%{python3_platform}-%{python3_version}/* src/
+# The options are: verbose, unit, functional
+%{python3} test.py -vuf
 
 %files -n python3-%{modname}
 %license doc/licenses/ZopePublicLicense.txt LICENSES.txt
@@ -108,6 +83,10 @@ export WITH_CYTHON=true
 %{python3_sitearch}/%{modname}-*.egg-info/
 
 %changelog
+* Thu Jan 06 2022 Charalampos Stratakis <cstratak@redhat.com> - 4.2.3-4
+- Security fix for CVE-2021-43818
+Resolves: rhbz#2032569
+
 * Wed Mar 24 2021 Charalampos Stratakis <cstratak@redhat.com> - 4.2.3-3
 - Security fix for CVE-2021-28957
 Resolves: rhbz#1941534