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Suggestion detail

Dismissed
Permalink CVE-2026-23553
2.9 LOW
  • CVSS version: 3.1
  • Attack vector (AV): LOCAL
  • Attack complexity (AC): HIGH
  • Privileges required (PR): NONE
  • User interaction (UI): NONE
  • Scope (S): UNCHANGED
  • Confidentiality impact (C): LOW
  • Integrity impact (I): NONE
  • Availability impact (A): NONE
updated 1 month, 3 weeks ago by @SigmaSquadron Activity log
  • Created automatic suggestion 1 month, 3 weeks ago
  • @SigmaSquadron dismissed 1 month, 3 weeks ago
x86: incomplete IBPB for vCPU isolation

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: 1) vCPU runs on CPU A, running task 1. 2) vCPU moves to CPU B, idle gets scheduled on A. Xen skips IBPB. 3) On CPU B, guest kernel switches from task 1 to 2, issuing IBPB. 4) 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.

References

Affected products

Xen
  • ==consult Xen advisory XSA-479

Matching in nixpkgs

pkgs.xen

Type-1 hypervisor intended for embedded and hyperscale use cases

pkgs.xenomapper

Utility for post processing mapped reads that have been aligned to a primary genome and a secondary genome and binning reads into species specific, multimapping in each species, unmapped and unassigned bins

pkgs.nxengine-evo

Complete open-source clone/rewrite of the masterpiece jump-and-run platformer Doukutsu Monogatari (also known as Cave Story)

pkgs.grub2_pvgrub_image

PvGrub2 image for booting PV Xen guests

  • nixos-unstable -
    • nixpkgs-unstable
    • nixos-unstable-small

pkgs.grub2_pvhgrub_image

PvGrub2 image for booting PVH Xen guests

  • nixos-unstable -
    • nixpkgs-unstable
    • nixos-unstable-small

Package maintainers

Already fixed.