CVE-2026-43249

Guest crash via concurrent Xen 9pfs teardown

Published May 6, 2026 · Updated May 6, 2026

Double-free in the Linux kernel Xen 9pfs front end allows attackers controlling a back end to crash the guest kernel. Concurrent XenStore back-end change notifications can make xen_9pfs_front_changed invoke xen_9pfs_front_free twice for the same front-end state. Exploitation requires a Xen guest with the 9pfs front end present and bound; the demonstrated consequence is a general-protection fault that interrupts the guest.

CVSS severity8.8
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Double-free in the Linux kernel Xen 9pfs front end allows attackers controlling a back end to crash the guest kernel. Concurrent XenStore back-end change notifications can make xen_9pfs_front_changed invoke xen_9pfs_front_free twice for the same front-end state. Exploitation requires a Xen guest with the 9pfs front end present and bound; the demonstrated consequence is a general-protection fault that interrupts the guest.

The record

CVE
CVE-2026-43249
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-415, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <59e7707492576bdbfa8c1dbe7d90791df31e4773
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a5d00dff97118a32fcf5fec7a4c3f864c4620c4e
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bf841d43f7a33d75675ba7f4e214ac1c67913065
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ce8ded2e61f47747e31eeefb44dc24a2160a7e32

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <59e7707492576bdbfa8c1dbe7d90791df31e4773; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a5d00dff97118a32fcf5fec7a4c3f864c4620c4e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bf841d43f7a33d75675ba7f4e214ac1c67913065; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ce8ded2e61f47747e31eeefb44dc24a2160a7e32

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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