{
  "version": "https://jsonfeed.org/version/1.1",
  "title": "Xen XSA-523: malicious guest can read and write any VM's memory, including dom0, via grant copy (CVE-2026-102703, CVE-2026-102704) · updates",
  "home_page_url": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703",
  "feed_url": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703/feed.json",
  "description": "Two flaws in the Xen hypervisor's grant copy operation let a malicious guest VM read and write arbitrary memory belonging to other domains, including dom0, breaking VM isolation on the host. Xen caches already-validated data during batches of grant copies on the same page, but re-validated it incorrectly: frame numbers and grant references could be mixed up (CVE-2026-102703), and the check limiting copy-by-frame-number to the caller's own memory was misplaced (CVE-2026-102704). Every Xen version from 4.6 onward is vulnerable and there is no mitigation. The Xen Project published patches for xen-unstable through 4.17.x on Nov 3 2026; XCP-ng 8.3 and Qubes OS 4.3 shipped fixed packages that need a host or dom0 reboot, while Debian stable releases were still listed as vulnerable on Nov 4. Found by Anthropic using Claude and validated by Ada Logics; no exploitation has been reported.",
  "language": "en",
  "_pwn": {
    "slug": "xen-xsa-523-grant-copy-guest-escape-cve-2026-102703",
    "severity": "critical",
    "status": "live",
    "patchStatus": "partial",
    "rss": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703/feed.xml",
    "llms": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703/llms.txt",
    "json": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703.json"
  },
  "items": [
    {
      "id": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703#2026-11-03-9266f683",
      "url": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703#2026-11-03-9266f683",
      "title": "Xen XSA-523: malicious guest can read and write any VM's memory, including dom0, via grant copy (CVE-2026-102703, CVE-2026-102704): Xen Project publishes XSA-523 (CVE-2026-102703, CVE-2026-102704) with patches for xen-unstable through Xen 4.17.x; no known mitigation.",
      "content_text": "Xen XSA-523: malicious guest can read and write any VM's memory, including dom0, via grant copy (CVE-2026-102703, CVE-2026-102704): Xen Project publishes XSA-523 (CVE-2026-102703, CVE-2026-102704) with patches for xen-unstable through Xen 4.17.x; no known mitigation.\n\nSource: https://xenbits.xen.org/xsa/advisory-523.html",
      "date_published": "2026-11-03T00:00:00.000Z",
      "external_url": "https://xenbits.xen.org/xsa/advisory-523.html",
      "tags": [
        "critical"
      ]
    },
    {
      "id": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703#2026-11-03-bf084938",
      "url": "https://pwn.watch/i/xen-xsa-523-grant-copy-guest-escape-cve-2026-102703#2026-11-03-bf084938",
      "title": "Xen XSA-523: malicious guest can read and write any VM's memory, including dom0, via grant copy (CVE-2026-102703, CVE-2026-102704): XCP-ng releases xen-4.17.7-4.2.xcpng8.3 and Qubes OS publishes fixed Xen 4.19.6-3 packages for Qubes 4.3; both require a host or dom0 reboot.",
      "content_text": "Xen XSA-523: malicious guest can read and write any VM's memory, including dom0, via grant copy (CVE-2026-102703, CVE-2026-102704): XCP-ng releases xen-4.17.7-4.2.xcpng8.3 and Qubes OS publishes fixed Xen 4.19.6-3 packages for Qubes 4.3; both require a host or dom0 reboot.\n\nSource: https://thehackernews.com/2026/11/xen-hypervisor-flaws-let-one-malicious.html",
      "date_published": "2026-11-03T00:00:00.000Z",
      "external_url": "https://thehackernews.com/2026/11/xen-hypervisor-flaws-let-one-malicious.html",
      "tags": [
        "critical"
      ]
    }
  ]
}