CVE-2026-46252 Linux Kernel Regulator Locking Vulnerability

Technical summary

CVE-2026-46252 addresses a locking violation in the Linux kernel's regulator core subsystem, specifically in the regulator_resolve_supply() function's error handling path. When late enabling of a supply regulator fails, the code calls _regulator_put() without holding the regulator_list_mutex, triggering lockdep warnings and creating a potential use-after-free scenario. The vulnerability is classified as CWE-667 (Improper Locking). The resolution involves: (1) replacing _regulator_put() with regulator_put(), which properly acquires the necessary lock internally; and (2) implementing additional mutex protection when clearing the supply pointer to prevent concurrent rdev access. This fix addresses a race condition in an error path that would otherwise allow unsynchronized modification of regulator state.

Business impact

This vulnerability primarily affects the availability and stability of Linux kernel-based systems. Affected systems could experience kernel panics, system hangs, or memory corruption when power regulator initialization encounters failures—conditions that might occur during boot, during dynamic power management transitions, or in edge-case hardware configurations. For enterprises deploying embedded Linux, IoT devices, or systems with complex power management requirements, unplanned kernel crashes directly impact operational uptime. While the vulnerability requires privileged access (as indicated by the CVSS vector PR:L), the exposure is significant in multi-tenant or untrusted-driver environments where a malicious or buggy kernel module or privileged user could trigger the condition deliberately.

Affected systems

All Linux kernel versions containing the vulnerable regulator_resolve_supply() code are affected. The vulnerability is not confined to a specific distribution but rather resides in the upstream Linux kernel. Any system running a kernel version with this vulnerable code path—including servers, embedded systems, IoT devices, and specialized hardware using Linux—is potentially affected. Newer kernel releases from the Linux kernel project addressing this issue should be tracked through vendor advisories and kernel.org release notes. Users should consult their specific Linux distribution vendor (Red Hat, Canonical, SUSE, etc.) for backported patches to their supported kernel versions.

Exploitability

Exploitation requires local privileged access (PR:L per the CVSS vector) and the ability to trigger regulator supply initialization failures. The attack surface is limited to scenarios where: (1) a privileged user can load a malicious or misconfigured kernel module; (2) a misconfigured or failing power supply regulator is registered; or (3) dynamic power management operations are triggered under adverse conditions. The vulnerability is not remotely exploitable and does not grant privilege escalation. However, it can be leveraged by a privileged user to cause denial of service (system crash) with high reliability once the conditions are met. The lack of public exploit code and KEV designation suggests this remains a lower-priority exploitation target, though the issue should not be dismissed in threat environments with trusted but potentially buggy kernel code or supervised lab settings.

Remediation

Apply kernel patches from your Linux distribution vendor that address CVE-2026-46252. The fix requires updating to a patched kernel version. Consult your distribution's security advisory or kernel release notes (verify against the vendor advisory for specific patched version numbers). For users who compile custom kernels, apply the upstream fix to regulator_resolve_supply() as described in the Linux kernel patch. Testing should validate that regulator initialization and error paths function correctly across your target hardware configurations.

Patch guidance

Monitor your Linux distribution's security advisory channels for updates addressing this CVE. For production systems: (1) schedule kernel updates following your change management process; (2) test in a staging environment with similar power management hardware to ensure no regressions; (3) coordinate updates during maintenance windows to minimize downtime. For systems using generic distributions (Red Hat Enterprise Linux, Ubuntu LTS, SUSE, etc.), patches should become available within weeks of the vulnerability's publication. Embedded system vendors should also release updates for affected SoC kernels. Always verify patched kernel version numbers against official vendor advisories before deployment.

Detection guidance

Detection of this vulnerability's exploitation is challenging at runtime without kernel debugging tools. System administrators should monitor for: (1) unexpected kernel panics or oops messages containing 'regulator_resolve_supply' or '_regulator_put' in the call trace; (2) increased system hang events during power state transitions or regulator initialization; (3) kernel lockdep warnings (if debugging enabled) related to regulator_list_mutex. For detection and monitoring: run `dmesg` or review system logs for regulator-related warnings; use `uname -r` to verify kernel version against known-affected ranges; enable kernel lockdep in debug configurations to catch the race condition early in test environments.

Why prioritize this

This vulnerability merits medium priority for general enterprise environments but higher priority for systems with strict availability requirements or complex power management. The CVSS score of 5.5 (MEDIUM) reflects the local-only attack surface (AV:L) and privilege requirement (PR:L), offset by the high availability impact (A:H) from kernel crashes. Prioritize patching for: (1) critical infrastructure systems where unexpected crashes are costly; (2) embedded/IoT deployments with power management complexity; (3) multi-tenant cloud environments where untrusted kernel modules might be loaded; (4) systems in environments where kernel debugging or aggressive regulator changes occur.

Risk score, explained

The CVSS v3.1 score of 5.5 (MEDIUM, CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) reflects: Attack Vector (Local) = vulnerability requires local system access; Attack Complexity (Low) = no special conditions needed to trigger once local access is gained; Privileges Required (Low) = a privileged user can trigger the condition; User Interaction (None) = no user action is necessary; Scope (Unchanged) = impact is confined to the vulnerable system; Confidentiality (None) = no information disclosure; Integrity (None) = no data corruption of user data; Availability (High) = denial of service via kernel crash is highly likely. The score appropriately weights a reliability-impacting but local-only vulnerability.

Frequently asked questions