diff --git a/src/brpc/redis_reply.cpp b/src/brpc/redis_reply.cpp
index 14c76f4841..86d702b117 100644
--- a/src/brpc/redis_reply.cpp
+++ b/src/brpc/redis_reply.cpp
@@ -141,6 +141,12 @@ ParseError RedisReply::ConsumePartialIOBuf(butil::IOBuf& buf, int depth) {
             return PARSE_ERROR_NOT_ENOUGH_DATA;
         }
         const size_t len = str.size() - 1;
+        if (FLAGS_redis_max_allocation_size < 0 ||
+            len > (size_t)FLAGS_redis_max_allocation_size) {
+            LOG(ERROR) << "simple string exceeds max allocation size! max="
+                       << FLAGS_redis_max_allocation_size << ", actually=" << len;
+            return PARSE_ERROR_ABSOLUTELY_WRONG;
+        }
         if (len < sizeof(_data.short_str)) {
             // SSO short strings, including empty string.
             _type = (fc == '-' ? REDIS_REPLY_ERROR : REDIS_REPLY_STATUS);
diff --git a/test/brpc_redis_unittest.cpp b/test/brpc_redis_unittest.cpp
index 9095c82961..daf06224ee 100644
--- a/test/brpc_redis_unittest.cpp
+++ b/test/brpc_redis_unittest.cpp
@@ -1499,6 +1499,34 @@ TEST_F(RedisTest, memory_allocation_limits) {
         ASSERT_EQ(brpc::PARSE_ERROR_ABSOLUTELY_WRONG, err);
     }
     
+    {
+        // Simple string exceeding limit. Unlike bulk strings and arrays this
+        // branch had no cap, so a length >= 2^31 truncated the signed _length
+        // field to a negative value and later reads went out of bounds.
+        butil::IOBuf buf;
+        std::string large_status = "+";
+        large_status.append(2000, 'a');
+        large_status.append("\r\n");
+        buf.append(large_status);
+
+        brpc::RedisReply reply(&arena);
+        brpc::ParseError err = reply.ConsumePartialIOBuf(buf);
+        ASSERT_EQ(brpc::PARSE_ERROR_ABSOLUTELY_WRONG, err);
+    }
+
+    {
+        // Error string exceeding limit (same branch as simple string).
+        butil::IOBuf buf;
+        std::string large_error = "-";
+        large_error.append(2000, 'a');
+        large_error.append("\r\n");
+        buf.append(large_error);
+
+        brpc::RedisReply reply(&arena);
+        brpc::ParseError err = reply.ConsumePartialIOBuf(buf);
+        ASSERT_EQ(brpc::PARSE_ERROR_ABSOLUTELY_WRONG, err);
+    }
+
     // Test redis_command.cpp limits
     {
         // Test command string exceeding limit