CVE-2026-89458

Received Received - Intake

s390/dasd ESE Read Failure Leads to Uninitialized Memory Exposure

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: s390/dasd: Do not complete a failed ESE read as successful dasd_int_handler() completes an NRF read of an unallocated ESE track by calling ese_read() and unconditionally marking the request DASD_CQR_SUCCESS. dasd_eckd_ese_read() can return an error before it has zeroed the destination buffer: a failed sense-data parse or a current track outside the requested range both return early, leaving the destination pages untouched. The request is still completed successfully, so the block layer is handed stale / uninitialized memory instead of zeros. Check the ese_read() return value and fail the request through the normal error path instead of forcing DASD_CQR_SUCCESS.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-11

Last Modified

2026-09-11

Generated

2026-09-12

AI Q&A

2026-09-12

EPSS Evaluated

N/A

NVD

CVE-2026-89458

EUVD

EUVD-2026-76364

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves incorrect handling of failed ESE (Enhanced Storage Element) read operations on unallocated tracks in the s390/dasd driver. When a read fails, the system incorrectly marks the operation as successful and passes uninitialized or stale memory to the block layer instead of zeros, potentially exposing sensitive data.

Detection Guidance

This vulnerability is specific to the Linux kernel's s390/dasd driver and involves improper handling of ESE read operations. Detection requires checking kernel logs for errors related to dasd or ESE reads, such as failed sense-data parsing or out-of-range track errors. Use commands like dmesg | grep -i dasd or journalctl -k | grep -i ese to search for relevant errors.

Impact Analysis

This vulnerability could lead to data leaks if an attacker exploits it to read uninitialized memory containing sensitive information. Systems using affected Linux kernel versions with s390/dasd storage devices may be vulnerable to unauthorized data exposure.

Mitigation Strategies

Apply the latest kernel update provided by your Linux distribution to patch this vulnerability. If immediate patching is not possible, consider disabling the affected DASD driver module or restricting access to unallocated ESE tracks until the update is applied.

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