In this post, we will look into CVE-2022-24942, a security vulnerability discovered in the Micrium uC-HTTP server 3.01.01. The issue arises from a heap-based buffer overflow in the HTTP server functionality and, if exploited, could lead to remote code execution by sending a specially crafted HTTP request to the server. We will delve into the details of this vulnerability, analyze the code snippet where the flaw occurs, and discuss potential exploitation methods.

Vulnerability Details

CVE-2022-24942 is a critical vulnerability present in the HTTP Server functionality of Micrium uC-HTTP 3.01.01, an embedded web server designed for IoT devices and embedded systems. The vulnerability stems from a heap-based buffer overflow issue caused by insufficient input validation and memory allocation during HTTP request processing. An attacker could exploit this vulnerability to execute arbitrary code on the target system by sending a tailored HTTP request.

The vulnerability has been assigned a CVSSv3 base score of 9.8, indicating that it poses a high risk due to the potential of remote code execution, a lack of required authentication, and the broad scope of systems potentially affected.

Code Snippet

The flawed code snippet is present in the http_server.c source code file, inside the HTTP_ServerReq() function. Here, the embedded server attempts to allocate memory for an incoming HTTP request without properly validating the lengths of the various components of the request.

void HTTP_ServerReq(HTTP_SERVER *p_server,
                    HTTP_SERVER_REQ *p_req,
                    HTTP_SERVER_CONN *p_conn,
                    RTOS_ERR *p_err) {
  CPU_CHAR *buf;
  CPU_CHAR *method;
  CPU_CHAR *uri;
  CPU_CHAR *protocol;
  // Allocate memory for request buffer
  buf = (CPU_CHAR *)Mem_HeapAlloc(req_len,

  if (RTOS_ERR_CODE_GET(*p_err) != RTOS_ERR_NONE) {


Notice that the memory allocation (Mem_HeapAlloc()) relies on the req_len parameter, which is supposed to account for the total length of the HTTP request components (method, URI, and protocol). However, there is no proper validation of the lengths, potentially causing a buffer overflow when copying data from the input buffer into the allocated memory.

Exploit Details

To exploit this vulnerability, an attacker needs to craft a malicious HTTP request that contains excessively long request components, such as the HTTP method, URI, or protocol string. When the server processes the request, it might allocate insufficient memory, causing a heap-based buffer overflow. This condition could lead to remote code execution with the privileges of the uC-HTTP server.

A potential attack scenario could involve an IoT device with the uC-HTTP server exposed to the internet. An attacker, after scanning the network for open HTTP ports and identifying the target device, might send a crafted HTTP request to trigger the heap-based buffer overflow andsuccessfully execute arbitrary code on the device, effectively compromising it.

Original References

1. NIST National Vulnerability Database: CVE-2022-24942
2. Micrium uC-HTTP Website
3. Common Vulnerability Scoring System Calculator


CVE-2022-24942 is a critical heap-based buffer overflow vulnerability in Micrium uC-HTTP's HTTP server functionality that poses a significant threat to the security and reliability of IoT devices and embedded systems employing this software. It is vital for developers and security teams to patch the affected systems to protect against potential remote code execution attacks. Additionally, properly validating input lengths and ensuring correct memory allocation will help to mitigate similar vulnerabilities in the future.


Published on: 11/15/2022 21:15:00 UTC
Last modified on: 11/21/2022 16:19:00 UTC