Privilege Escalation in Firefox WebRender

Compliance Impact

CVE-2026-12289 is a high-impact privilege escalation vulnerability that allows attackers to gain elevated privileges within affected applications such as Firefox and Thunderbird. This elevated access could potentially lead to unauthorized system access or further exploitation.

While the provided information does not explicitly mention compliance with standards like GDPR or HIPAA, vulnerabilities that enable privilege escalation and unauthorized access can increase the risk of data breaches or unauthorized data processing, which may impact compliance with such regulations.

Therefore, organizations using affected versions should apply the fixes promptly to mitigate risks that could lead to non-compliance with data protection and privacy regulations.

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Executive Summary

CVE-2026-12289 is a high-impact privilege escalation vulnerability found in the Graphics: WebRender component of Mozilla Firefox.

This vulnerability allows an attacker to gain elevated privileges within the Firefox application, which could enable further exploitation or unauthorized actions.

It affects Firefox ESR 115.36 and earlier, Firefox ESR 140.11 and earlier, and Firefox versions before 152, and has been fixed in Firefox 152, Firefox ESR 140.12, and Firefox ESR 115.37.

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Impact Analysis

This vulnerability can allow an attacker to escalate their privileges within the Firefox application.

With elevated privileges, an attacker could potentially perform unauthorized actions, gain further system access, or compromise the system beyond the browser.

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Mitigation Strategies

To mitigate the CVE-2026-12289 vulnerability, you should update your Firefox browser to a fixed version.

• Update to Firefox 152 or later if you are using the standard release.
• If using Firefox ESR, update to ESR 115.37 or later.
• Alternatively, update to Firefox ESR 140.12 or later if you are on the ESR 140 branch.

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Detection Guidance

This vulnerability affects specific versions of Firefox and Thunderbird related to the Graphics: WebRender component. Detection primarily involves identifying if vulnerable versions of these applications are installed on your system.

To detect the presence of vulnerable versions, you can check the installed version of Firefox or Thunderbird using the following commands:

• For Firefox: firefox --version
• For Thunderbird: thunderbird --version

If the version is earlier than Firefox 152, Firefox ESR 140.12, or Thunderbird 152 / Thunderbird 140.12, the system is vulnerable.

There are no specific network detection commands or signatures provided in the available resources for this vulnerability.

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