CVE-2022-27672

What it actually does

Speculative execution on SMT-enabled AMD processors can use a branch target from the sibling thread following an SMT mode switch, enabling cross-thread information disclosure via side-channel observation.

Why it matters to the business

Organizations using affected AMD processors face elevated risk of sensitive data leakage between co-located workloads on the same core, potentially impacting confidentiality of customer data, intellectual property, or cryptographic material without requiring elevated privileges beyond local execution.

How an attack unfolds

An attacker with local code execution on one SMT thread crafts a sequence that triggers an SMT mode switch, then uses timing or cache side channels to observe speculative execution artifacts originating from the sibling thread, extracting secrets such as keys or memory contents.

How to fix it

Apply the latest processor firmware and microcode updates from AMD for affected models; where firmware is unavailable, disable SMT via BIOS settings or operating system controls as a compensating control.

How to confirm the fix worked

Verify processor microcode revision matches or exceeds the version containing the fix for this speculative execution behavior; confirm SMT configuration changes take effect via CPUID or OS interfaces and re-test speculative execution paths if possible.

Typical attack path

1. Gain local code execution on a system with SMT enabled on a vulnerable AMD processor
2. Align execution timing with an SMT mode switch event
3. Prime microarchitectural state to induce speculative use of sibling thread targets
4. Measure side-channel leakage to recover sensitive information from the sibling context

How to detect it

Monitor for unusual cache or timing side-channel activity originating from local processes; review system logs for SMT mode switch events correlated with high-privilege or unexpected process execution.

What your security team should do

• Prioritize firmware updates for internet-facing or high-value systems running affected AMD processors
• Evaluate SMT disablement on systems processing sensitive data if updates cannot be applied promptly
• Monitor vendor advisories for additional affected models and updated fixed firmware releases