In this post, we will analyze the recently discovered vulnerability in rtf2html v.2., a popular tool used for converting Rich Text Format (RTF) files into Hypertext Markup Language (HTML) files. This vulnerability, identified as CVE-2022-43148, is a heap overflow in the component /rtf2html/./rtf_tools.h, which can be exploited to cause various security issues such as data corruption, information disclosure, or even remote code execution in affected systems.

The CVE-2022-43148 vulnerability is documented in the following sources

1. CVE Details:
2. National Vulnerability Database (NVD):
3. Exploit Database:

Code Snippet

The vulnerability occurs due to insufficient input validation and error handling when processing a specially crafted RTF file. The heap overflow is caused by a buffer overflow in the process_input() function, located in rtf_tools.h. A simplified version of the vulnerable code snippet is as follows:

// rtf_tools.h
void process_input(FILE *input_file) {
  char buffer[1024];

  while (!feof(input_file)) {
    fgets(buffer, sizeof(buffer), input_file);
    // Perform RTF-to-HTML conversion.

Exploit Details

To exploit this vulnerability, an attacker can create a malicious RTF file with a specially crafted string that exceeds the size of the buffer variable (1024 bytes). When the fgets() function is called to read the input file, a buffer overflow occurs, leading to a heap overflow. This can result in unexpected program behavior, data corruption, or information disclosure.

In certain conditions, the attacker may also be able to execute arbitrary code on the affected systems, although this requires further exploitation techniques such as a return-oriented programming (ROP) attack, heap spraying, or other heap exploitation methods.

For a proof-of-concept (PoC), an exploit script like the following could be used to generate a malicious RTF file:

file_contents = "\\rtf1"
file_contents += "A" * 2048  # Overflow the buffer variable.
file_contents += "\\par}"
with open("malicious_file.rtf", "w") as f:


Developers using rtf2html v.2. are advised to update to the latest version, which includes proper input validation and error handling. Additionally, users should be cautious when opening RTF files from untrusted sources, as they could contain malicious content.


The CVE-2022-43148 vulnerability in rtf2html v.2. should not be taken lightly, as it poses a significant security risk to affected systems. Although the initial exploitation may only lead to heap overflow, there is potential for further exploitation and remote code execution. Affected users should update their software immediately to mitigate the risk of a successful attack exploiting this vulnerability.


Published on: 10/31/2022 19:15:00 UTC
Last modified on: 11/01/2022 19:01:00 UTC