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Linux Kernel EUVDEUVD-2026-49003

| CVE-2026-64291 MEDIUM
2026-07-25 Linux GHSA-6gx3-fvx8-mx4p
5.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.5 MEDIUM

Local low-privilege user triggers memory exhaustion via uncapped ioctl parameter; no confidentiality or integrity impact, availability impact is high.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
5.5 LOW
qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Analysis Generated
Aug 12, 2026 - 15:08 vuln.today
CVSS changed
Aug 12, 2026 - 15:07 NVD
5.5 (MEDIUM)
Patch available
Jul 25, 2026 - 11:18 EUVD
CVE Published
Jul 25, 2026 - 08:49 nvd
MEDIUM 5.5
CVE Published
Jul 25, 2026 - 08:49 cve.org
UNKNOWN (no severity yet)

DescriptionNVD

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

iommufd: Set veventq_depth upper bound

iommufd_veventq_alloc() accepts any !0 veventq_depth from userspace, with an upper bound at U32_MAX.

This leaves a vulnerability where userspace can allocate excessively large queues to exhaust kernel memory reserves.

Cap the veventq_depth (maximum number of entries) to 1 << 19, matching the maximum number of entries in the SMMUv3 EVTQ (the largest use case today).

AnalysisAI

Memory exhaustion in the Linux kernel iommufd subsystem allows a local low-privileged user to crash the system by passing an uncapped veventq_depth value to iommufd_veventq_alloc(), which previously accepted any non-zero integer up to U32_MAX without validation. Exploitation requires local access with low privileges on a system where the iommufd device is accessible, making this primarily a concern for multi-tenant or virtualization hosts. No public exploit has been identified and EPSS at 0.21% (11th percentile) reflects minimal real-world exploitation interest at time of analysis.

Technical ContextAI

The iommufd subsystem provides a userspace interface for IOMMU (Input-Output Memory Management Unit) operations, commonly used in device passthrough and VFIO-based virtualization workloads. The function iommufd_veventq_alloc() allocates virtual event queues for IOMMU event notifications, with veventq_depth controlling the maximum number of queue entries. The flaw is the complete absence of an upper bound on this parameter: userspace could supply a value up to U32_MAX (4,294,967,295), causing the kernel to attempt proportionally massive memory allocations. The fix caps veventq_depth at 1 << 19 (524,288 entries), aligning with the SMMUv3 EVTQ (ARM System Memory Management Unit v3 Event Queue) - the largest practical use case. The CPE identifier is cpe:2.3:a:linux:linux:*. No CWE is formally assigned, but the root cause is an input validation weakness on a resource allocation parameter (functionally similar to CWE-770: Allocation of Resources Without Limits or Throttling).

RemediationAI

Apply the vendor-released kernel patches. Patched stable versions are Linux 6.18.39, 7.1.4, and 7.2-rc1; fix commits are available at https://git.kernel.org/stable/c/f565297edf316016be4a1a9e2eb9f39359313f43, https://git.kernel.org/stable/c/e7b5e55652746b1221b9c10ff80eae8a154101ba, and https://git.kernel.org/stable/c/6ebf2eb46fbd5b40393ff8fbb847ba96925beaff. As a compensating control prior to patching, restrict access to the iommufd device node (typically /dev/iommu) using filesystem permissions (chmod/chown) or mandatory access control policies (SELinux, AppArmor, or seccomp filters) to prevent untrusted local users from issuing ioctls to the subsystem. Trade-off: restricting /dev/iommu access will break any legitimate VFIO device passthrough or iommufd-dependent workloads for those users, so this control is only viable where such workloads are not running or can be migrated to privileged accounts.

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected

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EUVD-2026-49003 vulnerability details – vuln.today

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