diff --git a/.azure-pipelines/ci.yml b/.azure-pipelines/ci.yml
index b2ce9e75df6..2284a5fb36b 100644
--- a/.azure-pipelines/ci.yml
+++ b/.azure-pipelines/ci.yml
@@ -1,14 +1,14 @@
 variables:
   coverage: false
 
-trigger: ['main', '3.9', '3.8', '3.7']
+trigger: ['main', '3.10', '3.9', '3.8', '3.7']
 
 jobs:
 - job: Prebuild
   displayName: Pre-build checks
 
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-20.04
 
   steps:
   - template: ./prebuild-checks.yml
@@ -20,7 +20,7 @@ jobs:
   condition: and(succeeded(), eq(dependencies.Prebuild.outputs['docs.run'], 'true'))
 
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-20.04
 
   steps:
   - template: ./docs-steps.yml
@@ -40,7 +40,7 @@ jobs:
     testRunPlatform: macos
 
   pool:
-    vmImage: macos-10.14
+    vmImage: macos-10.15
 
   steps:
   - template: ./macos-steps.yml
@@ -52,12 +52,12 @@ jobs:
   condition: and(succeeded(), eq(dependencies.Prebuild.outputs['tests.run'], 'true'))
 
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-20.04
 
   variables:
     testRunTitle: '$(build.sourceBranchName)-linux'
     testRunPlatform: linux
-    openssl_version: 1.1.1k
+    openssl_version: 1.1.1l
 
   steps:
   - template: ./posix-steps.yml
@@ -78,12 +78,12 @@ jobs:
     )
 
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-20.04
 
   variables:
     testRunTitle: '$(Build.SourceBranchName)-linux-coverage'
     testRunPlatform: linux-coverage
-    openssl_version: 1.1.1k
+    openssl_version: 1.1.1l
 
   steps:
   - template: ./posix-steps.yml
diff --git a/.azure-pipelines/pr.yml b/.azure-pipelines/pr.yml
index 9360d37baec..1a3bf75ed4c 100644
--- a/.azure-pipelines/pr.yml
+++ b/.azure-pipelines/pr.yml
@@ -1,14 +1,14 @@
 variables:
   coverage: false
 
-pr: ['main', '3.9', '3.8', '3.7']
+pr: ['main', '3.10', '3.9', '3.8', '3.7']
 
 jobs:
 - job: Prebuild
   displayName: Pre-build checks
 
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-20.04
 
   steps:
   - template: ./prebuild-checks.yml
@@ -20,7 +20,7 @@ jobs:
   condition: and(succeeded(), eq(dependencies.Prebuild.outputs['docs.run'], 'true'))
 
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-20.04
 
   steps:
   - template: ./docs-steps.yml
@@ -38,7 +38,7 @@ jobs:
     testRunPlatform: macos
 
   pool:
-    vmImage: macos-10.14
+    vmImage: macos-10.15
 
   steps:
   - template: ./macos-steps.yml
@@ -52,12 +52,12 @@ jobs:
   condition: and(succeeded(), eq(dependencies.Prebuild.outputs['tests.run'], 'true'))
 
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-20.04
 
   variables:
     testRunTitle: '$(system.pullRequest.TargetBranch)-linux'
     testRunPlatform: linux
-    openssl_version: 1.1.1k
+    openssl_version: 1.1.1l
 
   steps:
   - template: ./posix-steps.yml
@@ -78,12 +78,12 @@ jobs:
     )
 
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-20.04
 
   variables:
     testRunTitle: '$(Build.SourceBranchName)-linux-coverage'
     testRunPlatform: linux-coverage
-    openssl_version: 1.1.1k
+    openssl_version: 1.1.1l
 
   steps:
   - template: ./posix-steps.yml
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 4081b36f926..c5d967dec7e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -138,7 +138,7 @@ jobs:
     needs: check_source
     if: needs.check_source.outputs.run_tests == 'true'
     env:
-      OPENSSL_VER: 1.1.1k
+      OPENSSL_VER: 1.1.1l
       PYTHONSTRICTEXTENSIONBUILD: 1
     steps:
     - uses: actions/checkout@v2
@@ -182,7 +182,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        openssl_ver: [1.1.1k, 3.0.0-beta1]
+        openssl_ver: [1.1.1l, 3.0.0-beta1]
     env:
       OPENSSL_VER: ${{ matrix.openssl_ver }}
       MULTISSL_DIR: ${{ github.workspace }}/multissl
@@ -229,7 +229,7 @@ jobs:
     needs: check_source
     if: needs.check_source.outputs.run_tests == 'true'
     env:
-      OPENSSL_VER: 1.1.1k
+      OPENSSL_VER: 1.1.1l
       PYTHONSTRICTEXTENSIONBUILD: 1
       ASAN_OPTIONS: detect_leaks=0:allocator_may_return_null=1:handle_segv=0
     steps:
diff --git a/Misc/NEWS.d/next/Windows/2021-08-27-23-50-02.bpo-45007.NIBlVG.rst b/Misc/NEWS.d/next/Windows/2021-08-27-23-50-02.bpo-45007.NIBlVG.rst
new file mode 100644
index 00000000000..fa076ee4c8b
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2021-08-27-23-50-02.bpo-45007.NIBlVG.rst
@@ -0,0 +1 @@
+Update to OpenSSL 1.1.1l in Windows build
diff --git a/PCbuild/get_externals.bat b/PCbuild/get_externals.bat
index 8a1ab21d743..ea85d98e12b 100644
--- a/PCbuild/get_externals.bat
+++ b/PCbuild/get_externals.bat
@@ -53,7 +53,7 @@ echo.Fetching external libraries...
 set libraries=
 set libraries=%libraries%                                       bzip2-1.0.6
 if NOT "%IncludeLibffiSrc%"=="false" set libraries=%libraries%  libffi-3.3.0
-if NOT "%IncludeSSLSrc%"=="false" set libraries=%libraries%     openssl-1.1.1k
+if NOT "%IncludeSSLSrc%"=="false" set libraries=%libraries%     openssl-1.1.1l
 set libraries=%libraries%                                       sqlite-3.35.5.0
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tcl-core-8.6.11.0
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tk-8.6.11.0
@@ -77,7 +77,7 @@ echo.Fetching external binaries...
 
 set binaries=
 if NOT "%IncludeLibffi%"=="false"  set binaries=%binaries% libffi-3.3.0
-if NOT "%IncludeSSL%"=="false"     set binaries=%binaries% openssl-bin-1.1.1k-1
+if NOT "%IncludeSSL%"=="false"     set binaries=%binaries% openssl-bin-1.1.1l
 if NOT "%IncludeTkinter%"=="false" set binaries=%binaries% tcltk-8.6.11.0
 if NOT "%IncludeSSLSrc%"=="false"  set binaries=%binaries% nasm-2.11.06
 
diff --git a/PCbuild/python.props b/PCbuild/python.props
index da65df58e22..42c67de4afa 100644
--- a/PCbuild/python.props
+++ b/PCbuild/python.props
@@ -63,8 +63,8 @@
     <libffiDir>$(ExternalsDir)libffi-3.3.0\</libffiDir>
     <libffiOutDir>$(ExternalsDir)libffi-3.3.0\$(ArchName)\</libffiOutDir>
     <libffiIncludeDir>$(libffiOutDir)include</libffiIncludeDir>
-    <opensslDir>$(ExternalsDir)openssl-1.1.1k\</opensslDir>
-    <opensslOutDir>$(ExternalsDir)openssl-bin-1.1.1k-1\$(ArchName)\</opensslOutDir>
+    <opensslDir>$(ExternalsDir)openssl-1.1.1l\</opensslDir>
+    <opensslOutDir>$(ExternalsDir)openssl-bin-1.1.1l\$(ArchName)\</opensslOutDir>
     <opensslIncludeDir>$(opensslOutDir)include</opensslIncludeDir>
     <nasmDir>$(ExternalsDir)\nasm-2.11.06\</nasmDir>
     <zlibDir>$(ExternalsDir)\zlib-1.2.11\</zlibDir>