CVE-2025-38352: Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability

CVE-2025-38352 is a time-of-check time-of-use (TOCTOU) race condition in the Linux kernel. CISA notes that this flaw has a high impact on confidentiality, integrity, and availability. For IT and security teams, it matters because successful exploitation of kernel race conditions can let an attacker escalate privileges or disrupt system stability on hosts that run the affected kernel.

Public detail is limited to the CWE-367 classification and the CISA summary; exact trigger conditions, affected subsystems, and fixed versions must be confirmed against the vendor advisory before any environment-specific decisions.

How it works

CWE-367 describes a classic TOCTOU race: the kernel checks a condition (for example, a permission, file state, or resource attribute) and later uses that result, but an attacker can change the underlying state in the window between the check and the use. In a kernel context this often involves concurrent threads, processes, or user-controlled objects that race against privileged code paths.

An attacker who can influence the raced object may cause the kernel to act on stale or attacker-controlled data. Outcomes can include privilege escalation, information disclosure, or denial of service, consistent with the high impact CISA attributes to confidentiality, integrity, and availability. No public exploit mechanics or proof-of-concept details are supplied in the available facts, so defenders should treat any claimed exploit code as unverified until the vendor advisory is reviewed.

Am I affected? How to find it in your systems

The vulnerability resides in the Linux kernel, so any system running a Linux kernel—physical servers, virtual machines, containers that share the host kernel, cloud instances, and embedded devices—is potentially in scope. Inventory steps include:

• Collect kernel version strings with uname -r or equivalent package queries (rpm -q kernel, dpkg -l linux-image-*, etc.) across the estate.
• Map those versions against the fixed releases listed in the vendor advisory; do not assume any particular release is safe without that confirmation.
• Identify high-value hosts (domain controllers, jump boxes, container hosts, multi-tenant systems) that allow untrusted local users or unprivileged code execution, because local race conditions typically require some ability to run code on the target.
• Review kernel logs (dmesg, journalctl -k) and audit records for anomalous privilege transitions, unexpected capability grants, or crashes that coincide with local activity; these are generic indicators only and must be correlated with the specific advisory guidance.

Cloud and managed Kubernetes environments should also check the provider’s kernel image versions and any BOD 22-01 guidance that applies to the service.

How to remediate

The primary remediation is to apply the vendor-supplied kernel update that addresses CVE-2025-38352. Follow the distribution or upstream instructions exactly; rebuild or reboot as required so that the patched kernel is running. After patching:

• Verify the running kernel version matches the fixed release.
• Re-enable any temporarily disabled features only after confirming they are no longer vulnerable.
• For cloud workloads, apply the provider’s patched images or follow BOD 22-01 guidance; if no mitigation is available, discontinue use of the affected product as directed by CISA.

Hardening measures that reduce the attack surface for kernel race conditions include restricting unprivileged user namespaces, limiting CAP_SYS_ADMIN and similar capabilities, and ensuring that only trusted code runs with elevated privileges. These steps complement, but do not replace, the vendor patch.

If you can't patch immediately

Until the patched kernel can be deployed, reduce risk with compensating controls:

• Segment systems so that untrusted users or workloads cannot reach hosts that still run the vulnerable kernel.
• Disable or tightly restrict features that commonly participate in TOCTOU races (for example, user namespaces or certain file-system operations) if the advisory or distribution guidance permits it.
• Apply virtual patching or host-based intrusion-prevention rules that detect patterns associated with local privilege-escalation attempts, while recognizing that race conditions are timing-sensitive and hard to signature reliably.
• Increase monitoring of privilege-escalation events, kernel oopses, and unexpected process capabilities; alert on anomalies and retain forensic artifacts.
• Where possible, move critical workloads to already-patched images or alternative platforms until the update window opens.

Document the residual risk and the planned patch timeline so that leadership understands the exposure.

If your data may have been exposed

Actively exploited kernel vulnerabilities can lead to full host compromise and subsequent data exposure. Known ransomware use of this CVE is not documented, but any successful privilege escalation should be treated as a potential breach. Review access logs, check for unauthorized accounts or persistence mechanisms, and rotate credentials that may have been accessible from the affected host. As an additional check, you can run a free exposure scan of your email addresses against known breach data sets to see whether related credentials have already appeared in public dumps.