CVE-2026-12327

Vulnerability

Memory safety bugs were present in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird ESR 140.11. These bugs showed evidence of memory corruption and could potentially be exploited to run arbitrary code [1]. The vulnerability was fixed in Firefox 152 and Firefox ESR 140.12 [1][2].

Exploitation

An attacker would need to craft a malicious web page or email (in the case of Thunderbird) that triggers one of the memory safety bugs. No other special network position or authentication is required beyond what is typical for web content processing [1]. The exact sequence of steps depends on the specific bug, but the bugs are presumed exploitable with enough effort [description].

Impact

Successful exploitation could allow an attacker to run arbitrary code on the victim's system, leading to full compromise of confidentiality, integrity, and availability [1]. The impact is rated high [1][2].

Mitigation

The vulnerability is fixed in Firefox 152 (released June 16, 2026) and Firefox ESR 140.12 (released June 16, 2026) [1][2]. Users should update to these versions or later. No workaround is available; updating is the only mitigation.