CVE-2026-64291
Received Received - Intake

Memory Exhaustion in Linux Kernel iommufd

Publication date: 2026-07-25

Last updated on: 2026-07-25

Assigner: kernel.org

Description
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).

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Meta Information

Published
2026-07-25
Last Modified
2026-07-25
Generated
2026-07-25
AI Q&A
2026-07-25
EPSS Evaluated
N/A
NVD
CVE-2026-64291
EUVD
EUVD-2026-49003

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves the iommufd component, where userspace can allocate excessively large queues in the veventq_depth parameter. The issue arises because the function iommufd_veventq_alloc() accepts any non-zero value for veventq_depth up to U32_MAX, allowing userspace to exhaust kernel memory reserves by creating very large queues.

Detection Guidance

This vulnerability involves excessive queue allocation in the Linux kernel's iommufd component. Detection requires checking kernel logs for unusually large iommufd allocations or memory exhaustion events. Monitor for kernel messages indicating high memory usage or failed allocations in iommufd-related subsystems.

Impact Analysis

This vulnerability can lead to kernel memory exhaustion, causing system instability, crashes, or denial-of-service conditions. Attackers with local access could exploit it to degrade system performance or render services unavailable.

Mitigation Strategies

Update your Linux kernel to the patched version that includes the fix for CVE-2026-64291. The patch caps the veventq_depth to 1 << 19 to prevent excessive queue allocations. Check your distribution's security updates or kernel release notes for the specific version containing this fix.

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