CVE-2026-12296

Vulnerability

CVE-2026-12296 is a sandbox escape vulnerability in the Security: Process Sandboxing component of Firefox, reported by Yaqoub Aldurayhim [1][2]. The bug allows an attacker to break out of the content process sandbox, which is designed to isolate web content from the rest of the system. Affected versions include Firefox prior to version 152 and Firefox ESR prior to version 140.12 [1][2]. The vulnerability was addressed in Firefox 152 and Firefox ESR 140.12, both released on June 16, 2026 [1][2].

Exploitation

An attacker can trigger the sandbox escape by exploiting the flaw in the Process Sandboxing component. No additional authentication or user interaction beyond normal browsing is required; the attacker only needs to serve a crafted web page to the victim's browser [1][2]. The exact sequence of steps is not disclosed in the available references but likely involves abusing flawed sandbox restrictions to execute code outside the sandboxed process.

Impact

Successful exploitation allows the attacker to escape the content sandbox, potentially gaining the ability to execute arbitrary code with the privileges of the Firefox process outside the sandbox. This could lead to full compromise of the affected system, including data theft, installation of malware, or further privilege escalation [1][2]. The impact is rated high by Mozilla.

Mitigation

Mozilla has fixed this vulnerability in Firefox 152 and Firefox ESR 140.12, released on June 16, 2026 [1][2]. Users should update to these or later versions. No workarounds are available, and the vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog as of the publication date.