CVE-2026-79611

Guest crash via mishandled branch-tracing debug state

Published Oct 13, 2026 · Updated Oct 13, 2026

Denial of service in Xen's VMX state handling allows guest OS users to crash an HVM/PVH guest via branch-tracing debug state. The VM-entry state adjustment fails to accommodate branch tracing when debug exceptions are intercepted, single stepping is active, and STI/MovSS blocking is set. Exposure requires VMX hardware; the resulting entry failure is fatal to the guest, not a reported host crash.

CVSS severityUnavailable
Unscored
EPSS probability0.17%
Next 30 days · Oct 18, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Xen's VMX state handling allows guest OS users to crash an HVM/PVH guest via branch-tracing debug state. The VM-entry state adjustment fails to accommodate branch tracing when debug exceptions are intercepted, single stepping is active, and STI/MovSS blocking is set. Exposure requires VMX hardware; the resulting entry failure is fatal to the guest, not a reported host crash.

The record

CVE
CVE-2026-79611
Published
Oct 13, 2026
Updated
Oct 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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