CVE-2026-46016 Overview
CVE-2026-46016 is a NULL pointer dereference vulnerability in the Linux kernel's Xilinx remoteproc driver. The flaw resides in the receive callback path of the remoteproc/xlnx component, where the driver accessed inter-processor interrupt (IPI) buffer information without first validating that the incoming message pointer was non-NULL. When a non-buffered IPI is received, the message pointer can be NULL, causing the kernel to dereference an invalid address and crash. The upstream fix adds a NULL check so buffer information is only accessed when the IPI is actually buffered.
Critical Impact
A NULL pointer dereference in the Xilinx remoteproc receive callback can crash the Linux kernel, producing a denial-of-service condition on affected systems using Xilinx IPI-based remote processor communication.
Affected Products
- Linux kernel (mainline) prior to the patched commits
- Linux kernel stable trees containing the Xilinx remoteproc driver (drivers/remoteproc/xlnx_r5_remoteproc.c)
- Xilinx Zynq UltraScale+ and related platforms using IPI-based remoteproc communication
Discovery Timeline
- 2026-05-27 - CVE-2026-46016 published to NVD
- 2026-05-27 - Last updated in NVD database
Technical Details for CVE-2026-46016
Vulnerability Analysis
The Xilinx remoteproc driver (xlnx) enables the Linux kernel to manage remote processors such as the Cortex-R5 cores on Zynq UltraScale+ devices. Communication between the host kernel and the remote processor uses inter-processor interrupts (IPIs), which may be either buffered (carrying message payload data) or non-buffered (signaling only). The driver's receive callback handler processes incoming IPI notifications and previously assumed buffer data was always available.
When a non-buffered IPI fires, the callback receives a NULL message pointer. Dereferencing this pointer to read buffer information triggers a kernel oops, halting the affected execution context. The condition is reachable through normal IPI signaling between the host and the remote processor, making it relevant to any system using the driver in production.
Root Cause
The root cause is missing input validation in the receive callback: the handler accessed buffer fields without confirming the message argument was non-NULL [CWE-476]. The patched code introduces a guard that only reads buffer information when the IPI is buffered, preventing the NULL dereference.
Attack Vector
The vulnerability is triggered through the IPI communication path between the Linux host and a Xilinx remote processor. A non-buffered IPI delivered to the receive callback is sufficient to invoke the vulnerable code path. The impact is a kernel crash leading to denial of service on the affected device. The fix is distributed across five stable-tree commits referenced in the kernel git tree, including commit 06d0bed2552f and commit 8242579859a7.
No public exploitation code is referenced in the CVE data, and no entries exist in CISA KEV or Exploit-DB.
Detection Methods for CVE-2026-46016
Indicators of Compromise
- Kernel oops or panic messages referencing xlnx_r5_remoteproc or the remoteproc receive callback path in dmesg or /var/log/kern.log
- Unexpected reboots or system instability on Xilinx Zynq UltraScale+ platforms running remoteproc workloads
- Stack traces containing NULL pointer dereference signatures originating from the Xilinx IPI receive handler
Detection Strategies
- Inventory Linux hosts running kernels with the Xilinx remoteproc driver enabled and compare installed kernel versions against the patched stable releases referenced in the kernel git commits
- Monitor kernel ring buffer output for BUG: unable to handle kernel NULL pointer dereference events tied to remoteproc symbols
- Correlate device crash telemetry with remote processor lifecycle events (start, stop, IPI delivery) to identify trigger conditions
Monitoring Recommendations
- Forward kernel logs from embedded and edge devices to a centralized logging or SIEM platform for anomaly detection
- Alert on repeated kernel oops events from the same host class, which can indicate exposure to this defect under normal workload conditions
- Track kernel package versions across fleets to confirm patch deployment
How to Mitigate CVE-2026-46016
Immediate Actions Required
- Identify all Linux systems using the Xilinx remoteproc driver, particularly Zynq UltraScale+ platforms running Cortex-R5 firmware via xlnx_r5_remoteproc
- Upgrade to a Linux kernel version that includes the upstream fix from the referenced stable-tree commits
- For embedded products, rebuild and redeploy kernel images with the patch applied through the vendor BSP update process
Patch Information
The fix is committed to the Linux kernel stable trees. Five commit references are published: 06d0bed2552f, 38dd6ccfdfbb, 5d1451cb2cf6, 7ddbf2111677, and 8242579859a7. The patch adds a NULL check in the receive callback so that buffer information is only read when the IPI is buffered.
Workarounds
- Disable the Xilinx remoteproc driver (CONFIG_RPROC_XLNX_R5) in kernel configuration if remote processor functionality is not required
- Unload the xlnx_r5_remoteproc module on running systems that do not depend on remote processor communication
- Restrict workloads that exercise non-buffered IPI signaling until the patched kernel is deployed
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
