CVE-2026-99155

Guest crash via unchecked SCSI response shadow slot

Published Oct 28, 2026 · Updated Oct 28, 2026

NULL dereference in Linux 5.19 Xen SCSI frontend handling allows attackers to crash a guest via crafted backend responses. scsifront_do_response() checks the response request ID's range but dereferences its shadow entry without checking whether the slot is NULL. Exploitation requires control of the guest's SCSI backend responses; a spurious or duplicate response selecting an unused slot crashes the guest.

CVSS severityUnavailable
Unscored
EPSS probability0.19%
Next 30 days · Nov 1, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL dereference in Linux 5.19 Xen SCSI frontend handling allows attackers to crash a guest via crafted backend responses. scsifront_do_response() checks the response request ID's range but dereferences its shadow entry without checking whether the slot is NULL. Exploitation requires control of the guest's SCSI backend responses; a spurious or duplicate response selecting an unused slot crashes the guest.

The record

CVE
CVE-2026-99155
Published
Oct 28, 2026
Updated
Oct 28, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 28, 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=5.19
  2. Affected versionversion=6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 <15791e57f57f7050014d08cfe239d4aa1e6b94b0
  3. Affected versionversion=6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 <1d91ec793d6c80eca963d426e0da832d40a062df
  4. Affected versionversion=6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 <8c8222c255772713eb36cde695777a1fce224917

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.19; version=6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 <15791e57f57f7050014d08cfe239d4aa1e6b94b0; version=6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 <1d91ec793d6c80eca963d426e0da832d40a062df; version=6d1c2f48f3fcf5f42967938c8ba6b42ac6b44b43 <8c8222c255772713eb36cde695777a1fce224917

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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application 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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