diff --git a/.azure-pipelines/ci.yml b/.azure-pipelines/ci.yml
index 3feb85ae6561de..0fe754bb071ea3 100644
--- a/.azure-pipelines/ci.yml
+++ b/.azure-pipelines/ci.yml
@@ -57,7 +57,7 @@ jobs:
   variables:
     testRunTitle: '$(build.sourceBranchName)-linux'
     testRunPlatform: linux
-    openssl_version: 1.1.1g
+    openssl_version: 1.1.1k
 
   steps:
   - template: ./posix-steps.yml
@@ -83,7 +83,7 @@ jobs:
   variables:
     testRunTitle: '$(Build.SourceBranchName)-linux-coverage'
     testRunPlatform: linux-coverage
-    openssl_version: 1.1.1g
+    openssl_version: 1.1.1k
 
   steps:
   - template: ./posix-steps.yml
diff --git a/.azure-pipelines/pr.yml b/.azure-pipelines/pr.yml
index 2e94af35600cfc..2d32e6d49bcc0e 100644
--- a/.azure-pipelines/pr.yml
+++ b/.azure-pipelines/pr.yml
@@ -57,7 +57,7 @@ jobs:
   variables:
     testRunTitle: '$(system.pullRequest.TargetBranch)-linux'
     testRunPlatform: linux
-    openssl_version: 1.1.1g
+    openssl_version: 1.1.1k
 
   steps:
   - template: ./posix-steps.yml
@@ -83,7 +83,7 @@ jobs:
   variables:
     testRunTitle: '$(Build.SourceBranchName)-linux-coverage'
     testRunPlatform: linux-coverage
-    openssl_version: 1.1.1g
+    openssl_version: 1.1.1k
 
   steps:
   - template: ./posix-steps.yml
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index d6be2b68642660..39c349bf6e910b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -131,7 +131,7 @@ jobs:
     needs: check_source
     if: needs.check_source.outputs.run_tests == 'true'
     env:
-      OPENSSL_VER: 1.1.1f
+      OPENSSL_VER: 1.1.1k
     steps:
     - uses: actions/checkout@v2
     - name: Register gcc problem matcher
diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 788d6ce047b4af..d8d932a7652d15 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -25,7 +25,7 @@ jobs:
     name: 'Ubuntu (Coverage)'
     runs-on: ubuntu-latest
     env:
-      OPENSSL_VER: 1.1.1f
+      OPENSSL_VER: 1.1.1k
     steps:
     - uses: actions/checkout@v2
     - name: Install Dependencies
diff --git a/.travis.yml b/.travis.yml
index 6a22d20455b422..7050d2557a7fc6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,7 +10,7 @@ cache:
 
 env:
   global:
-    - OPENSSL=1.1.1f
+    - OPENSSL=1.1.1k
     - OPENSSL_DIR="$HOME/multissl/openssl/${OPENSSL}"
     - PATH="${OPENSSL_DIR}/bin:$PATH"
     - CFLAGS="-I${OPENSSL_DIR}/include"
diff --git a/Mac/BuildScript/build-installer.py b/Mac/BuildScript/build-installer.py
index 864661ec9e1b6c..25a6a24f564947 100755
--- a/Mac/BuildScript/build-installer.py
+++ b/Mac/BuildScript/build-installer.py
@@ -242,9 +242,9 @@ def library_recipes():
 
     result.extend([
           dict(
-              name="OpenSSL 1.1.1j",
-              url="https://www.openssl.org/source/openssl-1.1.1j.tar.gz",
-              checksum='cccaa064ed860a2b4d1303811bf5c682',
+              name="OpenSSL 1.1.1k",
+              url="https://www.openssl.org/source/openssl-1.1.1k.tar.gz",
+              checksum='c4e7d95f782b08116afa27b30393dd27',
               buildrecipe=build_universal_openssl,
               configure=None,
               install=None,
diff --git a/Misc/NEWS.d/next/Build/2021-03-26-09-16-34.bpo-43631.msJyPi.rst b/Misc/NEWS.d/next/Build/2021-03-26-09-16-34.bpo-43631.msJyPi.rst
new file mode 100644
index 00000000000000..4de4905a6bb082
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2021-03-26-09-16-34.bpo-43631.msJyPi.rst
@@ -0,0 +1 @@
+Update macOS, Windows, and CI to OpenSSL 1.1.1k.
diff --git a/PCbuild/get_externals.bat b/PCbuild/get_externals.bat
index 213fa66908c493..42afe2c841f9c7 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
-if NOT "%IncludeSSLSrc%"=="false" set libraries=%libraries%     openssl-1.1.1i
+if NOT "%IncludeSSLSrc%"=="false" set libraries=%libraries%     openssl-1.1.1k
 set libraries=%libraries%                                       sqlite-3.34.0.0
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tcl-core-8.6.10.0
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tk-8.6.10.0
@@ -77,7 +77,7 @@ echo.Fetching external binaries...
 
 set binaries=
 if NOT "%IncludeLibffi%"=="false"  set binaries=%binaries% libffi
-if NOT "%IncludeSSL%"=="false"     set binaries=%binaries% openssl-bin-1.1.1i
+if NOT "%IncludeSSL%"=="false"     set binaries=%binaries% openssl-bin-1.1.1k
 if NOT "%IncludeTkinter%"=="false" set binaries=%binaries% tcltk-8.6.10.0
 if NOT "%IncludeSSLSrc%"=="false"  set binaries=%binaries% nasm-2.11.06
 
diff --git a/PCbuild/python.props b/PCbuild/python.props
index 3fa774816a7530..5822ba13950f44 100644
--- a/PCbuild/python.props
+++ b/PCbuild/python.props
@@ -62,8 +62,8 @@
     <libffiDir>$(ExternalsDir)libffi\</libffiDir>
     <libffiOutDir>$(ExternalsDir)libffi\$(ArchName)\</libffiOutDir>
     <libffiIncludeDir>$(libffiOutDir)include</libffiIncludeDir>
-    <opensslDir>$(ExternalsDir)openssl-1.1.1i\</opensslDir>
-    <opensslOutDir>$(ExternalsDir)openssl-bin-1.1.1i\$(ArchName)\</opensslOutDir>
+    <opensslDir>$(ExternalsDir)openssl-1.1.1k\</opensslDir>
+    <opensslOutDir>$(ExternalsDir)openssl-bin-1.1.1k\$(ArchName)\</opensslOutDir>
     <opensslIncludeDir>$(opensslOutDir)include</opensslIncludeDir>
     <nasmDir>$(ExternalsDir)\nasm-2.11.06\</nasmDir>
     <zlibDir>$(ExternalsDir)\zlib-1.2.11\</zlibDir>
diff --git a/PCbuild/readme.txt b/PCbuild/readme.txt
index af2f1bfe0d41b9..7518b8389f55c0 100644
--- a/PCbuild/readme.txt
+++ b/PCbuild/readme.txt
@@ -169,7 +169,7 @@ _lzma
     Homepage:
         http://tukaani.org/xz/
 _ssl
-    Python wrapper for version 1.1.1i of the OpenSSL secure sockets
+    Python wrapper for version 1.1.1k of the OpenSSL secure sockets
     library, which is downloaded from our binaries repository at
     https://github.com/python/cpython-bin-deps.
 
diff --git a/Tools/ssl/multissltests.py b/Tools/ssl/multissltests.py
index 7afa1eea2efb20..598503f72dd7cb 100755
--- a/Tools/ssl/multissltests.py
+++ b/Tools/ssl/multissltests.py
@@ -48,7 +48,7 @@
 ]
 
 OPENSSL_RECENT_VERSIONS = [
-    "1.1.1j",
+    "1.1.1k",
     # "3.0.0-alpha12"
 ]