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Vulnerability DatabaseCVE-2026-23553
CVE-2026-23553:
NixOS vulnerability analysis and mitigation
In the context switch logic Xen attempts to skip an IBPB in the case of a vCPU returning to a CPU on which it was the previous vCPU to run. While safe for Xen's isolation between vCPUs, this prevents the guest kernel correctly isolating between tasks. Consider:
- vCPU runs on CPU A, running task 1.
- vCPU moves to CPU B, idle gets scheduled on A. Xen skips IBPB.
- On CPU B, guest kernel switches from task 1 to 2, issuing IBPB.
- vCPU moves back to CPU A. Xen skips IBPB again. Now, task 2 is running on CPU A with task 1's training still in the BTB.
Source: NVD
Related NixOS vulnerabilities:
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