CVE-2026-53030: Linux Kernel Renesas i3c Memory Leak Vulnerability

Technical summary

CVE-2026-53030 is a CWE-401 (Missing Release of Memory after Effective Lifetime) vulnerability in the Linux kernel's i3c master implementation for Renesas controllers. The renesas_i3c_i3c_xfers() function calls renesas_i3c_alloc_xfer() to allocate an xfer structure but never deallocates it before the function returns. The vulnerability was addressed by applying the __free(kfree) cleanup attribute, enabling automatic memory release when variables exit scope. This is a kernel-level resource management issue with local attack surface.

Business impact

Unpatched systems face potential service disruption through memory exhaustion attacks. A local attacker with user-level privileges can repeatedly invoke i3c transfer operations to leak kernel memory, eventually triggering out-of-memory conditions that degrade system performance, cause application failures, or force system crashes. Organizations relying on Renesas i3c controllers—common in embedded systems, automotive, and IoT deployments—should prioritize assessment and patching to maintain availability.

Affected systems

The vulnerability affects Linux kernel versions containing the vulnerable Renesas i3c master driver code. Systems using Renesas i3c controllers are in scope. This includes embedded systems, automotive platforms, and IoT devices that depend on the Renesas i3c driver for peripheral communication. Kernel distributions and vendors packaging Linux should verify the inclusion and status of this code path in their supported versions.

Exploitability

Exploitation requires local system access (AV:L) and standard user-level privileges (PR:L). No special conditions, user interaction, or elevated rights are necessary once an attacker has local presence. The CVSS 3.1 score of 5.5 (MEDIUM) reflects the local attack vector and requirement for authentication, but the high impact on availability (A:H) underscores the practical risk of repeated memory depletion attacks. No public exploit code or KEV listing currently exists.

Remediation

Apply the official Linux kernel patch incorporating the __free(kfree) cleanup attribute to the renesas_i3c_i3c_xfers() function. Verify the patch against the upstream kernel commit or your vendor's advisory. Prioritize updates to systems with Renesas i3c hardware that are exposed to untrusted local users.

Patch guidance

Check your Linux distribution's security advisories and kernel release notes for updates addressing this CVE. For systems running mainline Linux, the fix is available in kernel versions released after the June 24, 2026 publication date. Coordinate patching with your vendor's support schedule. If you maintain custom kernel configurations, verify that the Renesas i3c driver is included and that patches are applied to the source tree before compilation. Test in a staging environment before production deployment to confirm driver functionality and performance.

Detection guidance

Monitor kernel memory usage patterns on systems with Renesas i3c controllers, particularly if local user activity spikes in correlation with i3c operations. Kernel logs or memory monitoring tools may show OOM-killer invocations or memory pressure events. If available, enable kernel module instrumentation or use dynamic tracing (kprobes, tracepoints) to count allocations and deallocations in the renesas_i3c driver to identify leaks in live systems. Audit local user access and privilege assignments on affected hardware to reduce attack surface.

Why prioritize this

Although the CVSS score is MEDIUM, the vulnerability should be treated seriously because it is a denial-of-service vector with straightforward local exploitation and no mitigation other than patching. Systems with Renesas i3c hardware serving safety-critical or high-availability functions deserve rapid assessment and patching. Non-critical systems may follow standard patching cycles, but should not be deferred indefinitely.

Risk score, explained

The CVSS 3.1 score of 5.5 reflects a local attack vector, low-to-medium attack complexity, and requirement for authenticated (user-level) access. However, the high impact on availability (A:H) reflects the practical consequence: repeated exploitation exhausts kernel memory and forces system instability. The absence of confidentiality or integrity impact keeps the score in the MEDIUM range. For risk prioritization, consider your organization's deployment of Renesas i3c hardware, tolerance for denial-of-service events, and exposure of local user accounts.

Frequently asked questions