With the widespread adoption of WebAssembly (Wasm) for high-performance web applications, ensuring the security and reliability of Wasm code execution is crucial. This post discusses a critical bug (CVE-2025-1011) in the WebAssembly code generation, which could have caused unexpected crashes and might have allowed an attacker to achieve arbitrary code execution. This vulnerability affects Firefox < 135, Firefox ESR < 128.7, Thunderbird < 128.7, and Thunderbird < 135.

Vulnerability Details

The vulnerability resides in the WebAssembly code generation that could lead to crashes. An attacker could potentially exploit this issue by crafting malicious WebAssembly code and persuading a victim to execute it using a vulnerable version of Firefox or Thunderbird. This could result in a crash, and it might be possible for the attacker to leverage this to gain control over the affected device.

Here's a code snippet illustrating the issue

// Malformed WebAssembly code example
(module
  (type (func (result i32)))
  (func (type ) (result i32)
    i32.const 1337
  )
  (export "main" (func ))
)

You can find the original references below

- Mozilla Security Advisory: CVE-2025-1011 - WebAssembly code generation bug
- National Vulnerability Database: CVE-2025-1011 Detail

Thunderbird versions before 135

Users are advised to update their software to the latest versions immediately to avoid exposure to this vulnerability. In addition, general best practices such as only running code from trusted sources, avoiding suspicious websites, and keeping software up-to-date can help minimize the risk of exploitation.

Select "Help" (question mark icon), then click "About Firefox."

3. Firefox will check for updates and download them if available. Restart the browser to complete the update process.

To update Thunderbird, follow these steps

1. Click the menu button (three parallel horizontal lines) in the upper right corner of the application.

Select "Help" (question mark icon), then click "About Thunderbird."

3. Thunderbird will check for updates and download them if available. Restart the application to complete the update process.

Conclusion

CVE-2025-1011 serves as a reminder of the importance of rigorous security testing for web technologies like WebAssembly. Developers, users, and security researchers must collaborate to identify and address vulnerabilities before they can be exploited. Ensuring that you're using the latest versions of software is one of the best ways to protect yourself from potential risks. Stay safe, stay updated!

Timeline

Published on: 02/04/2025 14:15:31 UTC
Last modified on: 02/06/2025 19:31:38 UTC