CVE-2025-2857: Firefox Sandbox Escape - A Continued Threat for Windows Users Following Chrome's Vulnerability

Recently, we saw the emergence of a Chrome sandbox escape vulnerability (CVE-2025-2783) that presented a significant threat to users worldwide. In response to this, Firefox developers began scouring their code for similar issues, and their diligence has paid off, albeit in an alarming manner. This article will delve into the details of CVE-2025-2857 and discuss how a compromised child process can result in the parent process returning an unintentionally powerful handle, leading to a sandbox escape. Note that this issue only affects Firefox on Windows, while other operating systems remain unaffected.

Details of the Vulnerability

The original Chrome vulnerability (CVE-2025-2783) was exploited in the wild, and with the identification of CVE-2025-2857 in Firefox, users must remain on high alert. The Firefox vulnerability resides in the Inter-Process Communication (IPC) code, and it affects the following versions:

Firefox ESR versions earlier than 115.21.1

The following code snippet demonstrates the critical section of the IPC code, where the vulnerability can be exploited:

// Vulnerable IPC section in Firefox

function getParenthandle() {
  let handle = null;
  switch (os.type()) {
    case "Windows_NT":
      return ipcRenderer.sendSync("get-parent-handle", parentPid);
    default:
      return handle;
  }
  process.setuid(100);
  process.setgid(100);
}

Exploit Details

In the abovementioned code, a compromised child process can lead the parent process to return a powerful handle unintentionally. The sandbox escape is facilitated by the interaction between the child process and the parent process, which opens up the opportunity for potential attackers to exploit this vulnerability.

Original References

Mozilla has issued official advisories in response to CVE-2025-2857, which outline the details of the vulnerability and provide crucial security updates. To understand the vulnerability better and to learn how to secure your Firefox browser, refer to these original references:

1. Mozilla Foundation Security Advisory 2025-37
2. CVE-2025-2857 Detail
3. Mozilla Firefox releases

Mitigation and Conclusion

To protect yourself from CVE-2025-2857, ensure that your Firefox browser is updated to one of the following versions: Firefox 136..4, Firefox ESR 128.8.1, or Firefox ESR 115.21.1. Keeping your software up-to-date is a critical practice to maintain the security and stability of your devices and data.

In summary, CVE-2025-2857 represents a significant vulnerability for Firefox users on Windows, as it mirrors the recent Chrome sandbox escape (CVE-2025-2783). Users must promptly update their software to secure their devices and thwart potential attacks. While it is common for software to have vulnerabilities, it is the rapid response of developers and users to address these issues that will ultimately bolster the security ecosystem.

Timeline

Published on: 03/27/2025 14:15:55 UTC
Last modified on: 03/28/2025 16:15:30 UTC