# CVE-2026-79611: xen: For XSA-308 logic was introduced, as VMX VMEntry checks do not like the exact combination of state which occurs when...

CVE-2026-79611 is fixed in xen on 1 platform, first by DEBIAN-CVE-2026-79611, released October 19, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-79611
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0016
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 13, 2026

## Description

For XSA-308 logic was introduced, as VMX VMEntry checks do not like the exact combination of state which occurs when #DB in intercepted, Single Stepping is active, and blocked by STI/MovSS is active, despite this being a legitimate state to be in.  The resulting VMEntry failure is fatal to the guest.  Sadly there is another special sub-case of the above, with branch tracing enabled.  In that case the prior adjustment would still cause a VMentry failure, as before fatal to the guest.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | xen Debian 12.15 (bookworm) | 4.17.7+13-g2445b30a44-0+deb12u1 | [DEBIAN-CVE-2026-79611](https://patchblox.com/security/data/fix/linux/debian-cve-2026-79611.md) | Oct 19, 2026 |
| Linux | xen Debian 13.5 (trixie) | 4.20.4+39-gf1e1321c87-0+deb13u1 | [DEBIAN-CVE-2026-79611](https://patchblox.com/security/data/fix/linux/debian-cve-2026-79611.md) | Oct 19, 2026 |
| Linux | xen Debian 14 | 4.20.4+39-gf1e1321c87-1 | [DEBIAN-CVE-2026-79611](https://patchblox.com/security/data/fix/linux/debian-cve-2026-79611.md) | Oct 19, 2026 |
| Linux | xen sles 15.7 | 4.20.4_06-150700.3.49.2 | [SUSE-SU-2026:4942-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4942-1.md) | Nov 7, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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