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Interrupt Injection Attack Bypasses Spectre v2 Defenses on Intel and AMD CPUs
Researchers from MIT CSAIL have discovered "Interrupt Injection," a sophisticated Time-of-Check to Time-of-Use (TOCTOU) vulnerability that bypasses Spectre v2 mitigations on Intel and AMD CPUs. The attack exploits a critical timing window where an unprivileged user can trigger a hardware interrupt immediately after the branch predictor has been sanitized but before the kernel executes. This allows for the re-poisoning of the branch predictor, enabling speculative execution-based data leakage across privilege boundaries. The discovery exposes fundamental weaknesses in current microarchitectural defense implementations, necessitating immediate kernel-level updates to secure Linux-based systems against cross-privilege information disclosure.