CVE-2026-23280: Linux Kernel Buffer Overflow Vulnerability

CVE-2026-23280 Overview

A vulnerability has been identified in the Linux kernel's AMD XDNA accelerator driver (accel/amdxdna) where an integer overflow in the ubuf size calculation can lead to undersized memory allocation and potential memory corruption. This flaw occurs during buffer size computations, which when overflowed, results in allocating less memory than required, creating conditions for heap-based memory corruption.

Critical Impact

Integer overflow in kernel accelerator driver can lead to memory corruption, potentially enabling privilege escalation or system instability in systems using AMD XDNA accelerators.

Affected Products

• Linux Kernel (versions with accel/amdxdna driver)
• Systems utilizing AMD XDNA accelerator hardware

Discovery Timeline

• 2026-03-25 - CVE CVE-2026-23280 published to NVD
• 2026-03-25 - Last updated in NVD database

Technical Details for CVE-2026-23280

Vulnerability Analysis

The vulnerability resides in the AMD XDNA accelerator driver within the Linux kernel. The core issue involves an arithmetic operation that calculates buffer sizes without proper overflow checking. When user-controlled or large input values are processed, the size calculation can wrap around due to integer overflow, resulting in a value much smaller than intended.

When memory is subsequently allocated based on this corrupted size value, the kernel allocates an undersized buffer. Any subsequent operations that write data expecting the full buffer size will write beyond the allocated memory region, corrupting adjacent heap memory. This type of memory corruption in kernel space is particularly dangerous as it can potentially be leveraged for privilege escalation, denial of service, or arbitrary code execution with kernel privileges.

Root Cause

The root cause is the absence of integer overflow validation in the ubuf size calculation logic within the amdxdna accelerator driver. The calculation performed addition operations on size values without using safe arithmetic helpers, allowing the result to wrap around to a small value when the operands are large. The fix implements check_add_overflow() helpers to validate the size calculation before the allocation proceeds, ensuring that overflowed calculations are detected and handled safely.

Attack Vector

An attacker with local access to a system with AMD XDNA accelerator hardware could potentially exploit this vulnerability by triggering operations that cause the buffer size calculation to overflow. This would require the ability to interact with the accelerator driver, typically through device file operations or ioctl calls. The exploitation would involve:

1. Identifying input parameters that influence the ubuf size calculation
2. Providing values that cause the size arithmetic to overflow
3. Triggering the undersized allocation
4. Performing operations that write beyond the allocated buffer bounds

Since this is a kernel driver vulnerability, successful exploitation could result in kernel memory corruption, leading to system instability, denial of service, or potential privilege escalation.

Detection Methods for CVE-2026-23280

Indicators of Compromise

• Unexpected kernel panics or system crashes related to memory corruption
• Kernel oops messages referencing the amdxdna driver or related memory subsystems
• Abnormal behavior in AMD XDNA accelerator operations
• Memory allocation failures followed by corruption indicators in kernel logs

Detection Strategies

• Monitor kernel logs (dmesg) for oops, panics, or warnings from the amdxdna module
• Implement kernel memory debugging options such as KASAN (Kernel Address Sanitizer) to detect out-of-bounds memory access
• Use system auditing to track interactions with the AMD XDNA accelerator device files
• Deploy endpoint detection solutions capable of monitoring kernel-level anomalies

Monitoring Recommendations

• Enable kernel debug logging for the accelerator subsystem
• Configure alerting for unexpected kernel module crashes or restarts
• Monitor for unusual patterns in device file access to /dev/accel/* or related accelerator interfaces
• Implement centralized logging to correlate potential exploitation attempts across systems

How to Mitigate CVE-2026-23280

Immediate Actions Required

• Apply the kernel patches provided in the kernel stable branches immediately
• If patching is not immediately possible, consider disabling or unloading the amdxdna module on systems where it is not critical
• Restrict access to accelerator device files to authorized users only
• Monitor systems for signs of exploitation attempts

Patch Information

The Linux kernel maintainers have released patches addressing this vulnerability. The fix implements check_add_overflow() helpers to properly validate size calculations before memory allocation. The following commits contain the security fix:

• Kernel Git Commit 03808ab
• Kernel Git Commit 1500b31
• Kernel Git Commit 972bf4a

Update to a kernel version containing these patches to remediate the vulnerability.

Workarounds

• Unload the amdxdna kernel module if AMD XDNA accelerator functionality is not required: modprobe -r amdxdna
• Blacklist the module to prevent automatic loading by adding blacklist amdxdna to /etc/modprobe.d/blacklist.conf
• Restrict device file permissions for the accelerator to limit exposure to untrusted users
• Apply mandatory access control policies (SELinux, AppArmor) to constrain access to the accelerator driver

# Configuration example - Disable amdxdna module
# Add to /etc/modprobe.d/blacklist-amdxdna.conf
echo "blacklist amdxdna" | sudo tee /etc/modprobe.d/blacklist-amdxdna.conf

# Unload module if currently loaded
sudo modprobe -r amdxdna

# Update initramfs to apply blacklist at boot
sudo update-initramfs -u