{
  "cveId": "CVE-2026-23553",
  "url": "https://patchblox.com/security/cve/CVE-2026-23553",
  "summary": "CVE-2026-23553 is fixed in xen on 1 platform, first by SUSE-SU-2026:0306-1, released January 27, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "xen: 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...",
  "description": "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\u0027s 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\u0027s training still in the BTB.",
  "published": "2026-01-27T16:15:19Z",
  "severity": "low",
  "cvss": 2.9,
  "cvssVector": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
  "epss": 0.00145,
  "epssPercentile": 0.03774,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "xen",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "4.17.7-0\u002Bdeb12u1",
      "fix": "DEBIAN-CVE-2026-23553",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-23553",
      "released": "2026-01-28T16:16:16Z"
    },
    {
      "platform": "linux",
      "product": "xen",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "4.20.2\u002B37-g61ff35323e-0\u002Bdeb13u1",
      "fix": "DEBIAN-CVE-2026-23553",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-23553",
      "released": "2026-01-28T16:16:16Z"
    },
    {
      "platform": "linux",
      "product": "xen",
      "release": "Debian 14",
      "fixedVersion": "4.20.2\u002B37-g61ff35323e-1",
      "fix": "DEBIAN-CVE-2026-23553",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-23553",
      "released": "2026-01-28T16:16:16Z"
    },
    {
      "platform": "linux",
      "product": "xen",
      "release": "opensuse-leap 15.6",
      "fixedVersion": "4.18.5_10-150600.3.37.1",
      "fix": "SUSE-SU-2026:0306-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-0306-1",
      "released": "2026-01-27T16:15:19Z"
    },
    {
      "platform": "linux",
      "product": "xen",
      "release": "sles 15.7",
      "fixedVersion": "4.20.2_06-150700.3.25.1",
      "fix": "SUSE-SU-2026:0589-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-0589-1",
      "released": "2026-02-20T10:05:27Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T13:31:49Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}