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CVE-2026-46197 is a high-severity out-of-bounds write vulnerability in the Linux kernel’s AMD GPU driver component, specifically in the `drm/amdkfd` subsystem. The issue resides in the `kfd_ioctl_svm` function within drivers/gpu/drm/amd/amdkfd/kfd_chardev.c. When handling SVM (Shared Virtual Memory) ioctl requests from userspace, the driver fails to validate the `nattr` field against the actual allocated buffer size. This `nattr` field specifies the number of attributes that the user intends to pass. An attacker with local access and the ability to invoke ioctl calls on the `/dev/kfd` device can craft a malicious request where `nattr` exceeds the buffer’s capacity. Without proper bounds checking, the kernel then reads beyond the allocated memory region, leading to out-of-bounds access. This can result in arbitrary memory read/write, kernel panic, or potentially privilege escalation. The vulnerability affects Linux kernel versions from 5.14 up to, but not including, the fixed versions: 6.6.140, 6.12.90, 6.18.32, 7.0.9, and 7.1-rc2. The fix, introduced in commit 5eca8bfdfa456c3304ca77523718fe24254c172f, adds a validation step that checks `nattr` against the buffer size. Specifically, it ensures that `nattr` does not exceed the number of attributes that can fit within the provided buffer. The CVSS score is 7.8 (HIGH) with the vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating high impact on confidentiality, integrity, and availability. The vulnerability is categorized under CWE-787 (Out-of-bounds Write). This issue was discovered and fixed by the Linux kernel security team. Users are strongly advised to update their kernels to the patched versions to mitigate the risk.
DailyCVE Form:
Platform: Linux Kernel
Version: 5.14-6.18.32
Vulnerability: Out-of-bounds Write
Severity: 7.8 HIGH
date: 2026-05-28
Prediction: 2026-05-17
What Undercode Say
Check if system is vulnerable by probing kernel version
uname -r
Test for the vulnerability using a crafted ioctl (requires /dev/kfd access)
This is a conceptual example; actual exploitation requires significant expertise
cat << EOF > test_svm_ioctl.c
include <stdio.h>
include <fcntl.h>
include <sys/ioctl.h>
include <linux/kfd_ioctl.h>
int main() {
int fd = open("/dev/kfd", O_RDWR);
if (fd < 0) return 1;
struct kfd_ioctl_svm_args args = {
.nattr = 0xffffffff, // Malicious large value
.attrs_ptr = (uint64_t)some_buffer,
// ...
};
ioctl(fd, KFD_IOC_SVM, &args);
return 0;
}
EOF
Monitor kernel logs for signs of out-of-bounds access
dmesg | grep -i "kernel panic|out-of-bounds|svm ioctl"
Exploit
An unprivileged local attacker opens `/dev/kfd` and invokes the `KFD_IOC_SVM` ioctl, supplying a maliciously large `nattr` field that exceeds the size of the allocated buffer. The kernel, lacking validation, writes beyond the buffer bounds, leading to arbitrary kernel memory corruption. This can be chained with other techniques to escalate privileges or cause a denial-of-service.
Protection
- Update to a patched kernel version (6.6.140, 6.12.90, 6.18.32, 7.0.9, 7.1-rc2 or later).
- If immediate patching is not possible, restrict access to `/dev/kfd` by removing read/write permissions for unprivileged users.
- Apply the security fix by backporting commit `5eca8bfdfa456c3304ca77523718fe24254c172f` to the affected kernel source.
Impact
Successful exploitation of CVE-2026-46197 can lead to arbitrary kernel memory read/write, system crash (denial-of-service), and potentially privilege escalation to root. The CVSS score of 7.8 (High) reflects the significant impact on confidentiality, integrity, and availability. This vulnerability affects all Linux systems with AMD GPUs and the `amdkfd` driver loaded, including many workstations, servers, and cloud instances.
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Sources:
Reported By: nvd.nist.gov
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