CVE-2026-72086
Received Received - Intake

Memory Leak in Linux Kernel SCSI Subsystem

Vulnerability report for CVE-2026-72086, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-15

Last updated on: 2026-08-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: xen: scsiback: Free the command tag on the TMR submit-failure path scsiback_device_action() obtains a command tag in scsiback_get_pend_req() and submits a task-management request with target_submit_tmr(). When target_submit_tmr() fails it returns < 0 and scsiback jumps to the err: label, which sends a response but frees nothing, leaking the tag. Impact: a pvSCSI guest can leak the command tags of a LUN's session, stopping the LUN, by issuing VSCSIIF_ACT_SCSI_ABORT or RESET requests whenever target_submit_tmr() fails. transport_generic_free_cmd() cannot be used here. By the time target_submit_tmr() returns an error it has already run __target_init_cmd() (so se_cmd->cmd_kref is one, not zero), and on its target_get_sess_cmd() error path it has freed se_cmd->se_tmr_req via core_tmr_release_req() while leaving SCF_SCSI_TMR_CDB set and the pointer dangling. Letting the command release run target_free_cmd_mem() would then double-free se_tmr_req. Use the same helper, which returns just the tag, on this path too.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-17
Generated
2026-09-04
AI Q&A
2026-08-15
EPSS Evaluated
2026-09-03
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

Attack-Flow Graph

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Executive Summary

This vulnerability in the Linux kernel involves a memory leak in the scsiback driver. When a task-management request fails, the command tag obtained for the request is not freed, causing a leak. This can lead to the guest system being unable to use the LUN by issuing specific SCSI requests.

Detection Guidance

This vulnerability is specific to the Linux kernel's scsi subsystem, particularly in the xen: scsiback driver. Detection requires checking kernel logs for failed task-management requests or command tag leaks in pvSCSI environments. Monitor for errors related to scsiback_device_action() or target_submit_tmr() failures in system logs.

Impact Analysis

A malicious pvSCSI guest could exploit this flaw to stop a LUN from functioning by repeatedly triggering task-management request failures. This would disrupt storage operations for the affected system.

Compliance Impact

This vulnerability allows a pvSCSI guest to leak command tags, potentially stopping a LUN by issuing SCSI abort or reset requests. While it does not directly impact data privacy or security controls, it could lead to denial-of-service conditions affecting system availability, which may indirectly affect compliance with standards like GDPR (availability principle) or HIPAA (accessibility and integrity of data).

Mitigation Strategies

Apply the latest Linux kernel patches addressing this issue. If using Xen with pvSCSI, disable or restrict guest access to SCSI devices until patched. Monitor for LUN failures or command tag leaks as indicators of exploitation.

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