Listen to this Post
The CVE-2025-39778 vulnerability occurs in the Linux kernel’s NVMe over Fabrics (NVMe-oF) subsystem, specifically in the `nvmet_ctrl_state_show()` function. This function improperly accesses the `csts_state_names[]` array, which contains only six sparse entries, but the loop iterates seven times. This leads to an out-of-bounds read on the stack, potentially exposing sensitive kernel memory or causing undefined behavior. The issue is detectable via UBSAN (Undefined Behavior Sanitizer) and was patched by correcting the loop bounds.
DailyCVE Form:
Platform: Linux Kernel
Version: Pre-patch versions
Vulnerability: Out-of-bounds stack read
Severity: Medium
Date: 04/18/2025
What Undercode Say:
Exploitation:
- Trigger via crafted NVMe-oF admin command.
- Exploit relies on kernel stack layout.
- May leak adjacent stack data.
Detection:
dmesg | grep "UBSAN: array-index-out-of-bounds" perf probe -x /lib/modules/$(uname -r)/kernel/drivers/nvme -a nvmet_ctrl_state_show
Mitigation:
- Apply kernel patch from upstream.
- Disable NVMe-oF if unused:
rmmod nvmet
- Enable kernel hardening:
echo 1 > /proc/sys/kernel/kptr_restrict
Proof-of-Concept (Crash Trigger):
include <linux/nvme.h>
int main() {
struct nvme_ctrl ctrl;
ctrl.csts = 7; // Invalid state
nvmet_ctrl_state_show(&ctrl, NULL);
return 0;
}
Patch Verification:
git grep "csts_state_names" /usr/src/linux/drivers/nvme
Kernel Config Hardening:
CONFIG_UBSAN=y CONFIG_FORTIFY_SOURCE=2
References:
- Kernel commit: `https://git.kernel.org/…`
– CVE Details: `https://nvd.nist.gov/…`
Monitoring:
auditctl -k nvmet_overflow
Stack Protection:
gcc -fstack-protector-strong exploit.c
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
