CVE-2026-12312

Vulnerability

A memory safety bug was discovered in Firefox, reported by jayjayjazz. The vulnerability affects Firefox versions prior to 152 and Firefox ESR versions prior to 140.12. The specific component and nature of the memory safety issue are not detailed in the public advisory, but it is classified as a high-impact vulnerability [1][2]. The bug is tracked in Mozilla's Bugzilla as Bug 2040383, though the details are not publicly accessible [3].

Exploitation

The exploitation of this memory safety bug requires an attacker to craft a web page that triggers the memory corruption. No additional authentication or specific user interaction beyond visiting a malicious webpage is required. The attack vector is over the network via a web browser, as typical for memory safety bugs in Firefox [1].

Impact

Successful exploitation could lead to memory corruption, potentially allowing an attacker to crash the browser or execute arbitrary code in the context of the browser process. The impact is rated as high by Mozilla [1][2]. The specific CIA outcome (confidentiality, integrity, availability) is not explicitly stated, but memory safety bugs often lead to arbitrary code execution, which could compromise all three.

Mitigation

Mozilla addressed this vulnerability in Firefox 152 and Firefox ESR 140.12, released on June 16, 2026 [1][2]. Users should update to these versions immediately. No workaround is available for users who cannot upgrade. The vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog as of the publication date.