Firefox JIT Vulnerability Exposes Tor Browser Users to Remote Code Execution
A high-severity flaw in Firefox's SpiderMonkey JavaScript engine allows remote code execution simply by visiting a malicious page, directly impacting Tor Browser users on unpatched versions. Registered as CVE-2026-10702, the vulnerability stems from incorrect memory handling in the JIT compiler that leaves a dangling reference to freed memory, enabling arbitrary read and write primitives. Researchers demonstrated successful exploitation that can compromise the browser's content rendering process and facilitate user deanonymization or OS-level attacks. The same issue served as the initial stage in the IonStack exploit chain against ARM64 Android devices, where it was chained with CVE-2026-43499 in the Linux kernel to achieve root privileges. Mozilla addressed the issue in Firefox 151.0.3, and the Tor Project rolled out corresponding fixes in Tor Browser 15.0.19, which also incorporates the latest Firefox ESR updates.
BoletimSecJul 30, 2026Translated from Portuguese