diff --git a/sanic/http/http1.py b/sanic/http/http1.py
index 49a3ca96e7..c6b4662b87 100644
--- a/sanic/http/http1.py
+++ b/sanic/http/http1.py
@@ -273,9 +273,12 @@ async def http1_request_header(self):  # no cov
                 pos -= 2  # One CRLF stays in buffer
             else:
                 self.request_body = True
-                self.request_bytes_left = self.request_bytes = int(
-                    headers["content-length"]
-                )
+                try:
+                    self.request_bytes_left = self.request_bytes = (
+                        self._safe_int(headers["content-length"])
+                    )
+                except Exception:
+                    raise BadRequest("Bad content-length")
 
         # Remove header and its trailing CRLF
         del buf[: pos + 4]
@@ -514,7 +517,8 @@ async def read(self) -> Optional[bytes]:  # no cov
                 await self._receive_more()
 
             try:
-                size = int(buf[2:pos].split(b";", 1)[0].decode(), 16)
+                raw = buf[2:pos].split(b";", 1)[0].decode()
+                size = self._safe_int(raw, 16)
             except Exception:
                 self.keep_alive = False
                 raise BadRequest("Bad chunked encoding")
@@ -600,3 +604,9 @@ def set_header_max_size(cls, *sizes: int):
             *sizes,
             cls.HEADER_CEILING,
         )
+
+    @staticmethod
+    def _safe_int(value: str, base: int = 10) -> int:
+        if "-" in value or "+" in value or "_" in value:
+            raise ValueError
+        return int(value, base)
diff --git a/tests/test_cookies.py b/tests/test_cookies.py
index 18c01a3a0a..63c8de8183 100644
--- a/tests/test_cookies.py
+++ b/tests/test_cookies.py
@@ -402,7 +402,8 @@ def test_cookie_jar_delete_existing_cookie():
     encoded = [cookie.encode("ascii") for cookie in jar.cookies]
     # deletion cookie contains samesite=Strict as was in original cookie
     assert encoded == [
-        b'foo=""; Path=/; Domain=example.com; Max-Age=0; SameSite=Strict; Secure',
+        b'foo=""; Path=/; Domain=example.com; Max-Age=0; '
+        b"SameSite=Strict; Secure",
     ]
 
 
diff --git a/tests/test_exceptions.py b/tests/test_exceptions.py
index b945eadea0..8d931ba461 100644
--- a/tests/test_exceptions.py
+++ b/tests/test_exceptions.py
@@ -423,7 +423,7 @@ def test_request_middleware_exception_on_404(app: Sanic):
 
     @app.on_request
     def request_middleware(request):
-        value = next(counter)
+        next(counter)
         raise Exception
 
     @app.route("/")
diff --git a/tests/test_http.py b/tests/test_http.py
index 77e4f6fc3f..4db6f111a3 100644
--- a/tests/test_http.py
+++ b/tests/test_http.py
@@ -110,3 +110,58 @@ def test_url_encoding(client):
 
     assert b"400 Bad Request" in headers
     assert b"URL may only contain US-ASCII characters." in body
+
+
+@pytest.mark.parametrize(
+    "content_length",
+    (
+        b"-50",
+        b"+50",
+        b"5_0",
+        b"50.5",
+    ),
+)
+def test_invalid_content_length(content_length, client):
+    body = b"Hello" * 10
+    client.send(
+        b"POST /upload HTTP/1.1\r\n"
+        + b"content-length: "
+        + content_length
+        + b"\r\n\r\n"
+        + body
+        + b"\r\n\r\n"
+    )
+
+    response = client.recv()
+    headers, body = response.rsplit(b"\r\n\r\n", 1)
+
+    assert b"400 Bad Request" in headers
+    assert b"Bad content-length" in body
+
+
+@pytest.mark.parametrize(
+    "chunk_length",
+    (
+        b"-50",
+        b"+50",
+        b"5_0",
+        b"50.5",
+    ),
+)
+def test_invalid_chunk_length(chunk_length, client):
+    body = b"Hello" * 10
+    client.send(
+        b"POST /upload HTTP/1.1\r\n"
+        + b"transfer-encoding: chunked\r\n\r\n"
+        + chunk_length
+        + b"\r\n"
+        + body
+        + b"\r\n"
+        + b"0\r\n\r\n"
+    )
+
+    response = client.recv()
+    headers, body = response.rsplit(b"\r\n\r\n", 1)
+
+    assert b"400 Bad Request" in headers
+    assert b"Bad chunked encoding" in body