SpiderMonkey

New Spectre-v2 Variant Uses JIT Compiler Branch Target Reuse for Cross-Process Data Extraction

Researchers from the Netherlands and Italy have published a paper detailing a fresh Spectre-v2 attack that reuses branch predictor state instead of injecting new instructions. The technique leverages the JIT compiler cBPF inside the Linux kernel to train the branch target predictor, enabling speculative execution that leaks sensitive data such as hashed root passwords. Practical demonstrations extracted credentials from the su process in an average of three to five minutes on AMD, Intel, and ARM processors. Partial success was shown with SpiderMonkey in Firefox and GraalVM, although realistic end-to-end attacks were not achieved with those engines. The work also covers additional topics including forensic detection of attacks against 1C servers, a record Debian Linux kernel patch set, zero-day fixes in TeamViewer and Apple Core Graphics, and critical flaws in Dell Container Storage Modules.

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.