CVE-2026-89444: Linux Kernel Information Disclosure Vulnerability

CVE-2026-89444 Overview

CVE-2026-89444 is an information disclosure vulnerability in the Linux kernel's dell-wmi-sysman platform driver. The set_attribute() function populates the security area of the BIOS attribute request buffer with the current admin password through populate_security_buffer(), then dumps the entire request buffer with print_hex_dump_bytes(). This behavior writes the plaintext BIOS admin password to the kernel log, where privileged users or log-collection systems can read it.

The same defect was previously corrected on the password attribute path by commit d1a196e0a6dc ("platform/x86: dell-wmi-sysman: Don't hex dump plaintext password data"). This fix removes the remaining hex dump from the BIOS attribute path.

Critical Impact
The BIOS admin password can be written in cleartext to dmesg and persistent kernel logs, enabling credential recovery by any actor with log access.

Affected Products

Linux kernel builds that include the platform/x86: dell-wmi-sysman driver
Dell client systems using the WMI systems management interface on affected kernels
Distribution kernels prior to backport of the fixing commits listed in the kernel.org references

Discovery Timeline

2026-09-11 - CVE-2026-89444 published to NVD
2026-09-14 - Last updated in NVD database

Technical Details for CVE-2026-89444

Vulnerability Analysis

The dell-wmi-sysman driver exposes Dell BIOS attributes to userspace through sysfs. When userspace writes a new value to an attribute, set_attribute() builds a WMI request buffer. Part of that buffer, the security area, must carry the current BIOS admin password so firmware will accept the change.

After populate_security_buffer() copies the plaintext password into the buffer, the driver calls print_hex_dump_bytes() on the full request buffer. The resulting hex dump lands in the kernel ring buffer and any downstream log collector such as journald, rsyslog, or a centralized SIEM.

Any user or process able to read kernel logs can reconstruct the BIOS admin password from the hex dump. On systems where kernel logs are shipped off-host, the credential leaves the machine entirely. The impact is a persistent credential disclosure that survives reboots wherever logs are retained.

Root Cause

The root cause is a debug or diagnostic hex dump left on a code path that handles secret material. print_hex_dump_bytes() was applied to a buffer whose contents include the admin password copied in by populate_security_buffer(). The password attribute path had already been corrected by commit d1a196e0a6dc, but the BIOS attribute path retained the same insecure dump. This is a sensitive information exposure defect ([CWE-532]-style logging of credentials).

Attack Vector

Exploitation is local and requires the ability to read kernel log output. An attacker with CAP_SYSLOG, root, or membership in a log-reading group can run dmesg or read /var/log/kern.log to recover the password after any legitimate BIOS attribute write. In managed fleets, log-forwarding infrastructure may replicate the credential to backend systems, widening the exposure to anyone with access to log storage. The vulnerability does not itself grant code execution or privilege escalation, but a recovered BIOS admin password enables firmware-level configuration changes, Secure Boot manipulation, and persistence below the operating system.

No public proof-of-concept code is required beyond triggering a BIOS attribute write and inspecting kernel logs. See the kernel.org commit references for the exact code paths.

Detection Methods for CVE-2026-89444

Indicators of Compromise

Kernel log entries produced by print_hex_dump_bytes() originating from the dell-wmi-sysman driver that contain BIOS attribute request buffers.
Presence of hex-dump lines in dmesg, journalctl -k, or forwarded syslog streams correlated with sysfs writes under the Dell firmware attributes tree.
Historical archives or SIEM indexes retaining kernel messages from Dell endpoints where BIOS attributes were configured.

Detection Strategies

Query centralized log storage for hex-dump patterns emitted by the dell-wmi-sysman module and flag any matches for credential rotation.
Inventory running kernels across Dell hardware and compare against fixed versions referenced in the kernel.org stable commits.
Monitor for userspace processes writing to Dell firmware attribute sysfs entries and correlate with subsequent kernel log growth.

Monitoring Recommendations

Restrict and audit access to kernel logs, including membership in groups such as adm and systemd-journal.
Alert on any read of kernel log files or dmesg invocations by non-administrative accounts on Dell endpoints.
Track log-forwarding pipelines that carry kernel messages off-host and ensure retention policies account for possible credential exposure.

How to Mitigate CVE-2026-89444

Immediate Actions Required

Update affected Linux kernels to a version containing the fix from the kernel.org stable commits.
Rotate the Dell BIOS admin password on any system where a BIOS attribute was changed while the vulnerable driver was loaded.
Purge historical kernel logs, journal archives, and SIEM records that may contain hex dumps of the request buffer.

Patch Information

The fix removes the print_hex_dump_bytes() call from the BIOS attribute path in dell-wmi-sysman, mirroring the earlier fix for the password attribute path in commit d1a196e0a6dc. Corrected code is available in the following stable kernel commits: 22222f92b0a5, 23ba9a18896e, 26f554f9f0fb, 44ec7f111330, 83c80495e45e, ceeee18c9279, and eb73b9d51490. Apply the update packaged by your distribution vendor.

Workarounds

Blacklist the dell-wmi-sysman module on systems that do not require Dell BIOS attribute management from Linux.
Restrict kernel log readability by tightening permissions on /dev/kmsg, journal files, and the adm and systemd-journal groups.
Avoid writing to Dell BIOS attributes from Linux until the patched kernel is installed, and manage BIOS settings through firmware setup instead.

bash

# Prevent the vulnerable driver from loading until the kernel is patched
echo 'blacklist dell-wmi-sysman' | sudo tee /etc/modprobe.d/cve-2026-89444.conf
sudo depmod -a

# Restrict dmesg to root only to limit credential exposure via kernel log
sudo sysctl -w kernel.dmesg_restrict=1
echo 'kernel.dmesg_restrict=1' | sudo tee /etc/sysctl.d/99-dmesg-restrict.conf