CVE-2025-27465Network attack vector

Whole-host crash via incorrect replay-stub exception metadata

Published Jul 16, 2025 · Updated Nov 4, 2025

Denial of service in Xen 4.9 and later allows guest OS users to crash the entire x86 host through an HVM or PVH guest. The x86 instruction replay stub's flags-recovery path records incorrect exception-table metadata, so Xen treats an emulation exception as fatal rather than handling it. Exploitation requires code execution inside an HVM or PVH guest on an x86 host; PV guests and Arm hosts are unaffected, and the failure interrupts every guest on the host.

CVSS severity4.3
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Xen 4.9 and later allows guest OS users to crash the entire x86 host through an HVM or PVH guest. The x86 instruction replay stub's flags-recovery path records incorrect exception-table metadata, so Xen treats an emulation exception as fatal rather than handling it. Exploitation requires code execution inside an HVM or PVH guest on an x86 host; PV guests and Arm hosts are unaffected, and the failure interrupts every guest on the host.

The record

CVE
CVE-2025-27465
Published
Jul 16, 2025
Updated
Nov 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-755, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record 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 vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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.

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

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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