Linux Kernel TOCTOU Race Condition (CVE-2025-38352)

Historical catalog analysis: CISA added this entry on September 04, 2025. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2025-38352 is a Time-of-Check Time-of-Use (TOCTOU) race condition (CWE-367) within the Linux kernel. This class of vulnerability occurs when a system checks a condition (such as a permission or a file state) and then performs an action based on that check, but the state changes between the two operations. According to CISA, this flaw has a high impact on confidentiality, integrity, and availability.

Exposure and applicability

Because the Linux kernel is a foundational open-source component, exposure extends across various operating systems and hardware architectures. Specifically, the vulnerability affects:
* Linux Kernel Distributions: Systems running versions of the kernel that have not integrated the fix identified in commit 2c72fe18cc5f9f1750f5bc148cf1c94c29e106ff.
* Android Devices: The vulnerability is addressed in the Android security bulletin dated 2025-09-01, indicating applicability to Android-based mobile and embedded devices.

Infrastructure owners must verify their specific vendor’s patching status, as the integration of upstream kernel fixes varies by distribution.

Remediation priorities

Our analysis suggests prioritizing remediation based on the asset’s exposure level and the criticality of the data it handles.

1. Immediate Patching: Apply updates from Linux distributions or Android OEMs that incorporate the fix. For those managing their own kernel builds, the primary reference is the stable git commit 2c72fe18cc5f9f1750f5bc148cf1c94c29e106ff.
2. Federal Compliance: U.S. federal agencies are subject to a CISA-mandated remediation deadline of 2025-09-25.
3. Asset Inventory: Identify all instances of the Linux kernel in use, including containers and virtual machines, as these may require host-level updates to resolve the race condition.

How to validate remediation

Verification must move beyond simple version checks, which can be misleading due to backported patches in stable distributions. To prove exposure was reduced, defenders should:
* Commit Verification: For custom or upstream kernels, verify that commit 2c72fe18cc5f9f1750f5bc148cf1c94c29e106ff is present in the build history.
* Vendor Attestation: Cross-reference installed package versions against official security advisories from the specific OS vendor (e.g., Red Hat, Ubuntu, or Android OEM) to ensure the fix for CVE-2025-38352 was explicitly included.
* Configuration Audit: Ensure that updated kernels are actively running in memory via a system reboot; a patched binary on disk does not mitigate an active race condition in a running kernel.

Limits and open questions

While the fix is available upstream, there is residual risk associated with the time lag between the upstream commit and vendor distribution. It remains unknown if this vulnerability has been leveraged by specific ransomware campaigns. Furthermore, because TOCTOU vulnerabilities are often dependent on precise timing and system load, standard scanning tools may not reliably detect the presence of the flaw or the effectiveness of a mitigation without deep kernel-level inspection.

Source and editorial note

CVE-2025-38352: Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability · Source date: September 04, 2025 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: September 07, 2025. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: October 03, 2026 at 00:34 UTC.

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