CVE-2025-38077 Overview
CVE-2025-38077 is a buffer overflow vulnerability in the Linux kernel's dell-wmi-sysman platform driver. The flaw resides in the current_password_store() function within platform/x86. When a user writes an empty string to the sysfs interface, the length variable evaluates to zero. The function then accesses buf[length - 1], producing an out-of-bounds write [CWE-787]. The Linux Verification Center identified the issue using the SVACE static analyzer. Successful exploitation requires local access with valid user privileges and can compromise kernel memory integrity.
Critical Impact
A local authenticated user can trigger an out-of-bounds write in the Linux kernel through the dell-wmi-sysman sysfs interface, potentially leading to kernel memory corruption and privilege escalation.
Affected Products
- Linux kernel 6.15 release candidates (rc1 through rc7)
- Multiple stable Linux kernel branches prior to the fix commits
- Debian Linux 11.0
Discovery Timeline
- 2025-06-18 - CVE-2025-38077 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-38077
Vulnerability Analysis
The dell-wmi-sysman driver exposes a sysfs attribute that allows administrators to submit the current BIOS password to the kernel through Windows Management Instrumentation (WMI). The write handler current_password_store() receives a user-supplied buf buffer and its length. The function attempts to strip a trailing newline character by inspecting the final byte at index length - 1. When the user writes an empty string, length equals zero, and the arithmetic underflows to a very large unsigned index. Accessing that index performs an out-of-bounds write against kernel memory.
The classification aligns with CWE-787, an out-of-bounds write weakness. Exploitation requires local access and low-privileged authentication because sysfs write access to the affected attribute is typically restricted to root or administrators on Dell systems that load the driver.
Root Cause
The root cause is missing input validation for zero-length writes. The handler assumed callers would always supply at least one byte before performing pointer arithmetic against the final index of the buffer. The upstream fix adds an explicit check that returns early when the received string is empty, preventing the underflow.
Attack Vector
An attacker with local access to a Dell endpoint running an affected kernel and the dell-wmi-sysman module can write an empty string to the corresponding sysfs attribute. The resulting out-of-bounds write corrupts adjacent kernel memory. Depending on the layout of surrounding structures, the corruption can produce denial of service or, with additional primitives, contribute to a privilege escalation chain. The attack does not traverse the network and requires no user interaction beyond issuing the sysfs write.
No verified proof-of-concept exploit code has been published. See the Linux kernel stable commit for the authoritative patch and technical details.
Detection Methods for CVE-2025-38077
Indicators of Compromise
- Kernel oops or panic messages referencing current_password_store or the dell-wmi-sysman module in dmesg and /var/log/kern.log.
- KASAN reports flagging an out-of-bounds write inside dell-wmi-sysman on kernels built with address sanitization enabled.
- Unexpected writes to /sys/class/firmware-attributes/dell-wmi-sysman/authentication/Admin/current_password or similar attributes by non-administrative processes.
Detection Strategies
- Inventory endpoints running Dell hardware with the dell-wmi-sysman module loaded, then correlate against installed kernel versions to identify unpatched hosts.
- Enable auditd rules that log write operations to firmware-attribute sysfs paths and alert on writes originating from unexpected user contexts.
- Monitor for kernel-mode crashes on Dell endpoints, as repeated panics may indicate exploitation attempts against this driver.
Monitoring Recommendations
- Forward dmesg and kernel audit events to a centralized logging platform and alert on module tainting or oops signatures involving dell-wmi-sysman.
- Track kernel package versions across the fleet and flag hosts still running vulnerable releases identified in the affected products list.
- Baseline normal writers of Dell firmware-attribute sysfs entries and alert on deviations.
How to Mitigate CVE-2025-38077
Immediate Actions Required
- Apply the stable kernel updates that contain the current_password_store() empty-string check across all Dell endpoints running affected releases.
- On Debian 11 systems, install the kernel package updates referenced in the Debian LTS Announcement.
- Restrict local shell and administrative access to Dell endpoints while patches are being staged.
Patch Information
The fix has been merged into multiple stable Linux kernel branches through the following commits: 4e89a40, 60bd13f8, 8594a12, 9706637, f864656, and fb7cde6. Debian users should install kernel packages provided by the Debian LTS Announcement.
Workarounds
- Blocklist the dell-wmi-sysman module on systems that do not require BIOS attribute management, preventing exposure of the vulnerable sysfs interface.
- Enforce strict filesystem permissions on /sys/class/firmware-attributes/dell-wmi-sysman/ to limit which accounts can write to password attributes.
- Reduce local access to affected endpoints and monitor privileged sessions until patches are applied.
# Blocklist the vulnerable module until the kernel patch is deployed
echo "blacklist dell-wmi-sysman" | sudo tee /etc/modprobe.d/blacklist-dell-wmi-sysman.conf
sudo modprobe -r dell_wmi_sysman 2>/dev/null || true
sudo update-initramfs -u
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
