diff --git a/lib/src/HttpRequestImpl.cc b/lib/src/HttpRequestImpl.cc
index c0b7f64706..20054c041a 100644
--- a/lib/src/HttpRequestImpl.cc
+++ b/lib/src/HttpRequestImpl.cc
@@ -78,9 +78,9 @@ void HttpRequestImpl::parseParameters() const
     if (!input.empty())
     {
         std::string_view::size_type pos = 0;
-        while ((input[pos] == '?' ||
-                isspace(static_cast<unsigned char>(input[pos]))) &&
-               pos < input.length())
+        while (pos < input.length() &&
+               (input[pos] == '?' ||
+                isspace(static_cast<unsigned char>(input[pos]))))
         {
             ++pos;
         }
@@ -139,9 +139,9 @@ void HttpRequestImpl::parseParameters() const
         type.find("application/x-www-form-urlencoded") != std::string::npos)
     {
         std::string_view::size_type pos = 0;
-        while ((input[pos] == '?' ||
-                isspace(static_cast<unsigned char>(input[pos]))) &&
-               pos < input.length())
+        while (pos < input.length() &&
+               (input[pos] == '?' ||
+                isspace(static_cast<unsigned char>(input[pos]))))
         {
             ++pos;
         }
diff --git a/lib/src/MultiPart.cc b/lib/src/MultiPart.cc
index 3b11af9170..eea95bbd2e 100644
--- a/lib/src/MultiPart.cc
+++ b/lib/src/MultiPart.cc
@@ -180,6 +180,8 @@ int MultiPartParser::parse(const HttpRequestPtr &req,
     std::string_view boundary{boundaryData, boundaryLen};
     if (boundary.size() > 2 && boundary[0] == '\"')
         boundary = boundary.substr(1, boundary.size() - 2);
+    if (boundary.empty())
+        return -1;
     std::string_view::size_type pos1, pos2;
     pos1 = 0;
     auto content = static_cast<HttpRequestImpl *>(req.get())->bodyView();
@@ -190,11 +192,15 @@ int MultiPartParser::parse(const HttpRequestPtr &req,
         if (pos1 == std::string_view::npos)
             break;
         pos1 += boundary.length();
+        if (content.size() - pos1 < 2)
+            return -1;
         if (content[pos1] == '\r' && content[pos1 + 1] == '\n')
             pos1 += 2;
         pos2 = content.find(boundary, pos1);
         if (pos2 == std::string_view::npos)
             break;
+        if (pos2 - pos1 < 4)
+            return -1;
         bool flag = false;
         if (content[pos2 - 4] == '\r' && content[pos2 - 3] == '\n' &&
             content[pos2 - 2] == '-' && content[pos2 - 1] == '-')
diff --git a/lib/tests/unittests/MultiPartParserTest.cc b/lib/tests/unittests/MultiPartParserTest.cc
index 0641203ada..07b61f8398 100644
--- a/lib/tests/unittests/MultiPartParserTest.cc
+++ b/lib/tests/unittests/MultiPartParserTest.cc
@@ -84,6 +84,23 @@ DROGON_TEST(MultiPartParserDashBoundary)
     CHECK(parser.getParameters().at("key1") == "value1");
 }
 
+DROGON_TEST(MultiPartParserRejectsNearbyBoundary)
+{
+    auto req = drogon::HttpRequest::newHttpRequest();
+    req->setMethod(drogon::Post);
+    req->addHeader("content-type", "multipart/form-data; boundary=A");
+    // The second boundary starts only three bytes into the body.
+    req->setBody(std::string("A\r\nA") + std::string(100, 'x'));
+
+    drogon::MultiPartParser parser;
+    CHECK(parser.parse(req) == -1);
+
+    // A boundary at the end leaves no bytes for the CRLF check.
+    req->setBody("A");
+    drogon::MultiPartParser parser2;
+    CHECK(parser2.parse(req) == -1);
+}
+
 DROGON_TEST(MultiPartDispositionParametersAreOrderIndependent)
 {
     static const std::string contentType =