CVE-2022-37051: Poppler pdfunite.cc Reachable Abort Vulnerability - Denial of Service Exploit and Remediation Steps

A security vulnerability, CVE-2022-37051, has been recently discovered in Poppler, a widely used PDF rendering library. The vulnerability affects version 22.07. of the software and could potentially allow a malicious user to cause a denial of service (DoS) attack by triggering a reachable abort. In this post, we will discuss the details of the vulnerability, provide code snippets to demonstrate the exploit, and provide links to original references for further information.

Summary of the Vulnerability

The issue resides in the pdfunite.cc file of Poppler 22.07., specifically in the main function. The main function lacks a necessary stream check before saving an embedded file, which leads to a reachable abort. If exploited, this vulnerability could crash the vulnerable software, causing a denial of service condition.

Original References

1. CVE-2022-37051 NVD Entry
2. Poppler GitHub Repository

Here is a code snippet demonstrating the issue in Poppler 22.07.'s pdfunite.cc file

int main (int argc, char *argv[])
{
  ...
  // Iterating through input files, parsing and saving them
  for (int i = 2; i < argc - 1; i++) {
    ...
    // Processing the embedded files
    for (int j = ; j < embFiles->getLength(); j++) {
      ...
      // Lacking stream check; could lead to a reachable abort
      fs::ofstream embOut(baseDir / embFilename, fs::ifstream::binary);
      embOut.write(fileStream->getCString(), fileStream->getLength());
      embOut.close();
      ...
    }
    ...
  }
  ...
}

In the above code snippet, the embOut.write() function is called without first checking if the fileStream variable is valid. This could lead to a reachable abort, causing the application to crash and resulting in a denial of service.

Mitigation and Remediation Steps

As of now, an official patch for Poppler 22.07. has not been released. However, you can implement a temporary mitigation by adding a stream check before the embOut.write() function, as shown in the following code snippet:

int main (int argc, char *argv[])
{
  ...
  // Iterating through input files, parsing and saving them
  for (int i = 2; i < argc - 1; i++) {
    ...
    // Processing the embedded files
    for (int j = ; j < embFiles->getLength(); j++) {
      ...
      // Adding the missing stream check before writing
      if (fileStream) {
        fs::ofstream embOut(baseDir / embFilename, fs::ifstream::binary);
        embOut.write(fileStream->getCString(), fileStream->getLength());
        embOut.close();
      }
      ...
    }
    ...
  }
  ...
}

Adding this check will prevent the reachable abort from occurring, thus mitigating the risk of a denial of service attack. It is recommended to apply the official patch from the Poppler developers once it becomes available.

Conclusion

CVE-2022-37051 is a critical vulnerability that affects Poppler 22.07. and may result in denial of service attacks. The vulnerability lies in the missing stream check in the main function in pdfunite.cc. As of now, there is no official patch, but implementing the temporary fix mentioned in this post can help mitigate the risk until the official patch is available.

For future updates and more information regarding this vulnerability, keep an eye on the official Poppler GitHub repository and the NVD entry for CVE-2022-37051.

Timeline

Published on: 08/22/2023 19:16:00 UTC
Last modified on: 10/16/2023 14:15:00 UTC