diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index d777f35ac208fd..91235c0309d29f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -111,8 +111,6 @@ jobs:
         run: echo "IMAGE_OS_VERSION=${ImageOS}-${ImageVersion}" >> "$GITHUB_ENV"
       - name: Install dependencies
         run: sudo ./.github/workflows/posix-deps-apt.sh
-      - name: Add ccache to PATH
-        run: echo "PATH=/usr/lib/ccache:$PATH" >> "$GITHUB_ENV"
       - name: Configure CPython
         run: |
           # Build Python with the libpython dynamic library
@@ -299,9 +297,6 @@ jobs:
     - name: Install OpenSSL
       if: steps.cache-openssl.outputs.cache-hit != 'true'
       run: python3 Tools/ssl/multissltests.py --steps=library --base-directory "$MULTISSL_DIR" --openssl "$OPENSSL_VER" --system Linux
-    - name: Add ccache to PATH
-      run: |
-        echo "PATH=/usr/lib/ccache:$PATH" >> "$GITHUB_ENV"
     - name: Configure CPython
       run: ./configure CFLAGS="-fdiagnostics-format=json" --config-cache --enable-slower-safety --with-pydebug --with-openssl="$OPENSSL_DIR"
     - name: Build CPython
@@ -356,9 +351,6 @@ jobs:
           --base-directory "$MULTISSL_DIR" \
           --awslc ${{ matrix.awslc_ver }} \
           --system Linux
-    - name: Add ccache to PATH
-      run: |
-        echo "PATH=/usr/lib/ccache:$PATH" >> "$GITHUB_ENV"
     - name: Configure CPython
       run: |
         ./configure CFLAGS="-fdiagnostics-format=json" \
@@ -459,9 +451,6 @@ jobs:
     - name: Install OpenSSL
       if: steps.cache-openssl.outputs.cache-hit != 'true'
       run: python3 Tools/ssl/multissltests.py --steps=library --base-directory "$MULTISSL_DIR" --openssl "$OPENSSL_VER" --system Linux
-    - name: Add ccache to PATH
-      run: |
-        echo "PATH=/usr/lib/ccache:$PATH" >> "$GITHUB_ENV"
     - name: Setup directory envs for out-of-tree builds
       run: |
         echo "CPYTHON_RO_SRCDIR=$(realpath -m "${GITHUB_WORKSPACE}"/../cpython-ro-srcdir)" >> "$GITHUB_ENV"
@@ -577,9 +566,6 @@ jobs:
     - name: Install OpenSSL
       if: steps.cache-openssl.outputs.cache-hit != 'true'
       run: python3 Tools/ssl/multissltests.py --steps=library --base-directory "$MULTISSL_DIR" --openssl "$OPENSSL_VER" --system Linux
-    - name: Add ccache to PATH
-      run: |
-        echo "PATH=/usr/lib/ccache:$PATH" >> "$GITHUB_ENV"
     - name: Configure CPython
       run: ./configure --config-cache --with-address-sanitizer --without-pymalloc --with-openssl="$OPENSSL_DIR"
     - name: Build CPython
diff --git a/.github/workflows/posix-deps-apt.sh b/.github/workflows/posix-deps-apt.sh
index 0b64367e6c4562..a2fac7c66db1d9 100755
--- a/.github/workflows/posix-deps-apt.sh
+++ b/.github/workflows/posix-deps-apt.sh
@@ -4,7 +4,6 @@ apt-get update
 apt-get -yq install \
     build-essential \
     pkg-config \
-    ccache \
     cmake \
     gdb \
     lcov \
diff --git a/.github/workflows/reusable-san.yml b/.github/workflows/reusable-san.yml
index 49876cf49260d9..b70f9b4b0d6259 100644
--- a/.github/workflows/reusable-san.yml
+++ b/.github/workflows/reusable-san.yml
@@ -66,9 +66,6 @@ jobs:
       env:
         SANITIZER: ${{ inputs.sanitizer }}
         SAN_LOG_OPTION: log_path=${{ github.workspace }}/san_log
-    - name: Add ccache to PATH
-      run: |
-        echo "PATH=/usr/lib/ccache:$PATH" >> "$GITHUB_ENV"
     - name: Configure CPython
       run: >-
         ./configure
diff --git a/.github/workflows/reusable-ubuntu.yml b/.github/workflows/reusable-ubuntu.yml
index 4bb4f535acb360..9032ac016e4810 100644
--- a/.github/workflows/reusable-ubuntu.yml
+++ b/.github/workflows/reusable-ubuntu.yml
@@ -63,9 +63,6 @@ jobs:
     - name: Install OpenSSL
       if: steps.cache-openssl.outputs.cache-hit != 'true'
       run: python3 Tools/ssl/multissltests.py --steps=library --base-directory "$MULTISSL_DIR" --openssl "$OPENSSL_VER" --system Linux
-    - name: Add ccache to PATH
-      run: |
-        echo "PATH=/usr/lib/ccache:$PATH" >> "$GITHUB_ENV"
     - name: Setup directory envs for out-of-tree builds
       run: |
         echo "CPYTHON_RO_SRCDIR=$(realpath -m "${GITHUB_WORKSPACE}"/../cpython-ro-srcdir)" >> "$GITHUB_ENV"
diff --git a/.github/workflows/reusable-wasi.yml b/.github/workflows/reusable-wasi.yml
index 68c5ef14cfe212..fb62f0d5164e07 100644
--- a/.github/workflows/reusable-wasi.yml
+++ b/.github/workflows/reusable-wasi.yml
@@ -38,8 +38,6 @@ jobs:
         mkdir "${WASI_SDK_PATH}" && \
         curl -s -S --location "https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-${WASI_SDK_VERSION}/wasi-sdk-${WASI_SDK_VERSION}.0-arm64-linux.tar.gz" | \
         tar --strip-components 1 --directory "${WASI_SDK_PATH}" --extract --gunzip
-    - name: "Add ccache to PATH"
-      run: echo "PATH=/usr/lib/ccache:$PATH" >> "$GITHUB_ENV"
     - name: "Install Python"
       uses: actions/setup-python@v6
       with:
diff --git a/Android/android.py b/Android/android.py
index 0a894a958a0165..b644be9cc64c7a 100755
--- a/Android/android.py
+++ b/Android/android.py
@@ -208,7 +208,7 @@ def make_build_python(context):
 def unpack_deps(host, prefix_dir):
     os.chdir(prefix_dir)
     deps_url = "https://github.com/beeware/cpython-android-source-deps/releases/download"
-    for name_ver in ["bzip2-1.0.8-3", "libffi-3.4.4-3", "openssl-3.0.19-1",
+    for name_ver in ["bzip2-1.0.8-3", "libffi-3.4.4-3", "openssl-3.5.5-0",
                      "sqlite-3.50.4-0", "xz-5.4.6-1", "zstd-1.5.7-1"]:
         filename = f"{name_ver}-{host}.tar.gz"
         download(f"{deps_url}/{name_ver}/{filename}")
diff --git a/Apple/__main__.py b/Apple/__main__.py
index 253bdfaab5520c..3261f368a88fc0 100644
--- a/Apple/__main__.py
+++ b/Apple/__main__.py
@@ -316,7 +316,7 @@ def unpack_deps(
     for name_ver in [
         "BZip2-1.0.8-2",
         "libFFI-3.4.7-2",
-        "OpenSSL-3.0.19-1",
+        "OpenSSL-3.5.5-1",
         "XZ-5.6.4-2",
         "mpdecimal-4.0.0-2",
         "zstd-1.5.7-1",
diff --git a/Doc/library/turtle.rst b/Doc/library/turtle.rst
index 234042c661f51a..20c659756fe1c1 100644
--- a/Doc/library/turtle.rst
+++ b/Doc/library/turtle.rst
@@ -16,6 +16,9 @@
 
    import os
    os.remove("my_drawing.ps")
+   # Destroy the turtle window after tests are complete
+   # Imported via star import in testsetup
+   bye()
 
 --------------
 
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 6619c87bcf5b93..b565b1d8a9e226 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -1345,6 +1345,17 @@ async def start_tls(self, transport, protocol, sslcontext, *,
         # have a chance to get called before "ssl_protocol.connection_made()".
         transport.pause_reading()
 
+        # gh-142352: move buffered StreamReader data to SSLProtocol
+        if server_side:
+            from .streams import StreamReaderProtocol
+            if isinstance(protocol, StreamReaderProtocol):
+                stream_reader = getattr(protocol, '_stream_reader', None)
+                if stream_reader is not None:
+                    buffer = stream_reader._buffer
+                    if buffer:
+                        ssl_protocol._incoming.write(buffer)
+                        buffer.clear()
+
         transport.set_protocol(ssl_protocol)
         conmade_cb = self.call_soon(ssl_protocol.connection_made, transport)
         resume_cb = self.call_soon(transport.resume_reading)
diff --git a/Lib/test/test_asyncio/test_streams.py b/Lib/test/test_asyncio/test_streams.py
index f93ee54abc6469..cae8c7c6f7c94c 100644
--- a/Lib/test/test_asyncio/test_streams.py
+++ b/Lib/test/test_asyncio/test_streams.py
@@ -819,6 +819,48 @@ async def client(addr):
         self.assertEqual(msg1, b"hello world 1!\n")
         self.assertEqual(msg2, b"hello world 2!\n")
 
+    @unittest.skipIf(ssl is None, 'No ssl module')
+    def test_start_tls_buffered_data(self):
+        # gh-142352: test start_tls() with buffered data
+
+        async def server_handler(client_reader, client_writer):
+            # Wait for TLS ClientHello to be buffered before start_tls().
+            await client_reader._wait_for_data('test_start_tls_buffered_data'),
+            self.assertTrue(client_reader._buffer)
+            await client_writer.start_tls(test_utils.simple_server_sslcontext())
+
+            line = await client_reader.readline()
+            self.assertEqual(line, b"ping\n")
+            client_writer.write(b"pong\n")
+            await client_writer.drain()
+            client_writer.close()
+            await client_writer.wait_closed()
+
+        async def client(addr):
+            reader, writer = await asyncio.open_connection(*addr)
+            await writer.start_tls(test_utils.simple_client_sslcontext())
+
+            writer.write(b"ping\n")
+            await writer.drain()
+            line = await reader.readline()
+            self.assertEqual(line, b"pong\n")
+            writer.close()
+            await writer.wait_closed()
+
+        async def run_test():
+            server = await asyncio.start_server(
+                server_handler, socket_helper.HOSTv4, 0)
+            server_addr = server.sockets[0].getsockname()
+
+            await client(server_addr)
+            server.close()
+            await server.wait_closed()
+
+        messages = []
+        self.loop.set_exception_handler(lambda loop, ctx: messages.append(ctx))
+        self.loop.run_until_complete(run_test())
+        self.assertEqual(messages, [])
+
     def test_streamreader_constructor_without_loop(self):
         with self.assertRaisesRegex(RuntimeError, 'no current event loop'):
             asyncio.StreamReader()
diff --git a/Misc/NEWS.d/next/Library/2025-12-06-16-14-18.gh-issue-142352.pW5HLX88.rst b/Misc/NEWS.d/next/Library/2025-12-06-16-14-18.gh-issue-142352.pW5HLX88.rst
new file mode 100644
index 00000000000000..13e38b118175b4
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-12-06-16-14-18.gh-issue-142352.pW5HLX88.rst
@@ -0,0 +1,4 @@
+Fix :meth:`asyncio.StreamWriter.start_tls` to transfer buffered data from
+:class:`~asyncio.StreamReader` to the SSL layer, preventing data loss when
+upgrading a connection to TLS mid-stream (e.g., when implementing PROXY
+protocol support).