What is the CVSS score of EUVD-2026-45644?

EUVD-2026-45644 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.2%.

Which versions of Linux Kernel are affected by EUVD-2026-45644?

Linux NVMe driver installations-particularly on systems with Thunderbolt-attached storage or PCIe link instability-face a kernel memory corruption vulnerability (CVSS 7.8) capable of triggering…. A patch is available.

How to fix or mitigate EUVD-2026-45644?

Within 24 hours, inventory Linux systems running affected kernel versions with NVMe, particularly those with Thunderbolt connectivity or documented PCIe stability issues; assess business criticality of affected production systems. Within 7 days, obtain and test the vendor-released kernel patch in staging environments matching production hardware configurations (especially Thunderbolt NVMe attached systems) to confirm compatibility and stability. Within 30 days, roll out the patched kernel version to all affected production systems in priority order (data centers first, then cloud instances), verify kernel logs show successful NVMe initialization post-reboot, and monitor IOMMU and PCIe error rates for 48 hours post-deployment on each wave.

Linux Kernel EUVD-2026-45644

| CVE-2026-64071 HIGH

Use After Free (CWE-416)

2026-07-19 Linux

GHSA-g774-9rm3-mcq6

Denial Of Service Linux Use After Free Memory Corruption Dell

7.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

7.8 HIGH

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

vuln.today AI

7.8 HIGH

Local access with low privilege needed to trigger device probe; UAF class supports full C/I/A potential despite primary observed impact being kernel crash.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from NVD.

CVSS VectorNVD

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Sep 03, 2026 - 15:11 vuln.today

CVSS changed

Sep 03, 2026 - 15:07 NVD

7.8 (HIGH)

Patch available

Jul 19, 2026 - 17:03 EUVD

CVE Published

Jul 19, 2026 - 15:39 nvd

HIGH 7.8

CVE Published

Jul 19, 2026 - 15:39 cve.org

UNKNOWN (no severity yet)

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

nvme-pci: fix use-after-free in nvme_free_host_mem()

nvme_free_host_mem() frees dev->hmb_sgt via dma_free_noncontiguous() but never clears the pointer afterward. This leads to a use-after-free if nvme_free_host_mem() is called twice in the same error path.

This can happen during nvme_probe() when nvme_setup_host_mem() succeeds in allocating the HMB (setting dev->hmb_sgt) but nvme_set_host_mem() fails with an I/O error:

nvme_setup_host_mem() nvme_alloc_host_mem_single() -> sets dev->hmb_sgt nvme_set_host_mem() -> fails with -EIO nvme_free_host_mem() -> frees hmb_sgt, but does NOT NULL it return error

nvme_probe() error path: nvme_free_host_mem() -> dev->hmb_sgt is stale, use-after-free

The second call dereferences the freed sgt, causing a NULL pointer dereference in iommu_dma_free_noncontiguous() when it accesses sgt->sgl->dma_address (the backing memory has been freed and zeroed).

This is reproducible on Thunderbolt-attached NVMe devices (e.g., OWC Envoy Express behind a Dell WD22TB4 dock) where the device intermittently returns I/O errors during HMB setup due to PCIe link instability.

BUG: kernel NULL pointer dereference, address: 0000000000000010 RIP: 0010:iommu_dma_free_noncontiguous+0x22/0x80 Call Trace: <TASK> dma_free_noncontiguous+0x3b/0x130 nvme_free_host_mem+0x30/0xf0 [nvme] nvme_probe.cold+0xcc/0x275 [nvme] local_pci_probe+0x43/0xa0 pci_device_probe+0xeea/0x290 really_probe+0xf9/0x3b0 __driver_probe_device+0x8b/0x170 driver_probe_device+0x24/0xd0 __driver_attach_async_helper+0x6b/0x110 async_run_entry_fn+0x37/0x170 process_one_work+0x1ac/0x3d0 worker_thread+0x1b8/0x360 kthread+0xf7/0x130 ret_from_fork+0x2d8/0x3a0 ret_from_fork_asm+0x1a/0x30 </TASK>

Fix this by setting dev->hmb_sgt to NULL after freeing it, so the second call takes the multi-descriptor path which safely handles the already-cleaned-up state.

AnalysisAI

Use-after-free (CWE-416) in the Linux kernel nvme-pci driver allows a local attacker or triggerable hardware condition to crash the kernel or potentially corrupt memory. The nvme_free_host_mem() function frees dev->hmb_sgt but never clears the pointer, so a double-call during an error path in nvme_probe() dereferences the freed and zeroed DMA structure, causing a NULL pointer dereference in iommu_dma_free_noncontiguous(). Observed reliably on Thunderbolt-attached NVMe devices with PCIe link instability; no public exploit or active exploitation identified at time of analysis.

Technical ContextAI

The Host Memory Buffer (HMB) feature in NVMe (PCIe-attached storage) allows the controller to use host DRAM as a cache. In nvme_probe(), nvme_setup_host_mem() first calls nvme_alloc_host_mem_single() to allocate a scatter-gather table (dev->hmb_sgt via dma_alloc_noncontiguous()) and then calls nvme_set_host_mem() to inform the controller. If nvme_set_host_mem() returns -EIO, nvme_free_host_mem() is called to clean up, but the pointer is not set to NULL after the free. The outer nvme_probe() error path then calls nvme_free_host_mem() a second time with the now-stale (freed and zeroed) dev->hmb_sgt pointer, triggering a NULL pointer dereference at offset 0x10 inside iommu_dma_free_noncontiguous() when it accesses sgt->sgl->dma_address. Affected Linux versions span from commit 63a5c7a4b4c49ad86c362e9f555e6f343804ee1d through the stable branches patched by commits 9525e3a6fbb1d126a22ab2ee86ddea25af581a7c, 7c89f474005d8377525d2991930b7432ee193a52, and b35a13036755c5803168a7cb93bc66035c3e65b8, corresponding to stable releases 6.18.34 and 7.0.11 and mainline 7.1.

RemediationAI

Apply the vendor-released patches for this bug: upgrade to Linux 6.18.34, 7.0.11, or 7.1 (or any downstream distribution kernel that incorporates commit b35a13036755c5803168a7cb93bc66035c3e65b8, 7c89f474005d8377525d2991930b7432ee193a52, or 9525e3a6fbb1d126a22ab2ee86ddea25af581a7c from git.kernel.org/stable). Ubuntu users should apply USN-8593-1 via standard package update. As a compensating control where immediate patching is not possible on systems with Thunderbolt NVMe exposure, disabling the nvme module's HMB feature via the kernel boot parameter nvme_core.hmb=0 (if exposed by distribution kernel) or blacklisting the specific device from HMB allocation would prevent the double-free path from being reached, at a minor NVMe performance cost. No workaround eliminates the underlying pointer-not-nulled defect; patching is the only complete fix.