External risk intelligence

Firefox and Thunderbird macOS WebGL Out of Bounds Memory Access Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2023-29531

This vulnerability affects client-side software (web browsers and email clients) running on macOS. Exploitation requires the user to interact with malicious content via the application, rather than the application itself serving as a public-facing network service or infrastructure component.

Out-of-bounds Write

Mozilla Firefox

before 112.0before 102.10

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A memory corruption vulnerability was identified in WebGL APIs that could lead to application crashes. This issue specifically impacts Firefox and Thunderbird on macOS. While the potential for exploitation exists, the primary concern for leadership is to confirm if these specific software and operating system combinations are in use within the organization.

Allows attackers to crash applications.
Affects Firefox and Thunderbird on macOS.
Confirm if affected software is in use.

Attack Path

How an attacker could exploit the issue

An attacker could target users on macOS who are running vulnerable versions of Firefox or Thunderbird. By directing the user to a specially crafted web page or a malicious email attachment that utilizes WebGL, the attacker could trigger an out-of-bounds memory access. This could lead to memory corruption, causing the application to crash and potentially allowing for further malicious actions.

Entry condition: User visits a malicious site.
Trigger point: WebGL API usage.
Resulting risk: Memory corruption and crashes.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to cause memory corruption in Firefox or Thunderbird on macOS through specially crafted WebGL content, potentially leading to a crash.

Browser and email client memory.
Malicious WebGL content interaction.
Application crash.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts client-side applications on macOS, specifically Firefox and Thunderbird. Ownership likely falls to endpoint security or client application management teams. The immediate first step is to identify all macOS systems running the affected software, confirm if they access untrusted content, and then plan remediation based on the risk of user interaction.

Endpoint or client application teams own remediation.
Verify macOS systems with affected software.
Plan user-based remediation and communication.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is Firefox and Thunderbird in the context of CVE-2023-29531?

Firefox is a web browser used for navigating the internet, and Thunderbird is an email client for managing messages. Both are complex applications that process various types of web content, including graphics rendered by WebGL APIs. This vulnerability specifically concerns how these applications handle memory on macOS systems.

What does out-of-bounds memory access mean for CVE-2023-29531?

This vulnerability involves a weakness class known as CWE-787, or Out-of-bounds Write. Essentially, the software fails to properly check memory boundaries when processing data through WebGL. This allows the application to write data outside its designated space, causing memory corruption that can lead to crashes or other unauthorized behaviors.

How is this WebGL memory corruption triggered?

The flaw is triggered when a user interacts with malicious content, such as visiting a compromised webpage or opening an email containing specifically crafted WebGL data. If a user does not visit untrusted sites or view malicious attachments using the affected macOS applications, the trigger path is not initiated.

Why does Halo Surface Signal categorize this as 'Very unlikely'?

Halo Surface Signal assesses this as 'Very unlikely' because the vulnerability impacts client-side software rather than a server. Since it requires a user to actively interact with malicious content on their macOS device, the application does not function as a public-facing network service that an attacker could reach directly over the internet.

What should I do if I use these applications on macOS?

Your first step is to identify all macOS endpoints running versions of Firefox older than 112 or Thunderbird older than 102.10. Once identified, ensure these applications are updated to the latest versions provided by the vendor to receive the necessary security patches.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.