CVE-2026-43253Network attack vector

Host hang via spinlocked completion busy-wait

Published May 6, 2026 · Updated May 6, 2026

Denial of service in the Linux Kernel AMD IOMMU driver allows remote attackers to hang affected systems through sustained network traffic. The iommu_completion_wait() path calls wait_on_sem() while holding iommu->lock with interrupts disabled, busy-waiting on a hardware-updated command semaphore that does not require the lock. Exposure requires an AMD system with IOMMU-translated DMA protecting a PCIe NIC, iommu.strict=1, and enough received traffic to sustain IOMMU flush pressure; repeated triggering hangs or severely stalls the host kernel.

CVSS severity7.5
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux Kernel AMD IOMMU driver allows remote attackers to hang affected systems through sustained network traffic. The iommu_completion_wait() path calls wait_on_sem() while holding iommu->lock with interrupts disabled, busy-waiting on a hardware-updated command semaphore that does not require the lock. Exposure requires an AMD system with IOMMU-translated DMA protecting a PCIe NIC, iommu.strict=1, and enough received traffic to sustain IOMMU flush pressure; repeated triggering hangs or severely stalls the host kernel.

The record

CVE
CVE-2026-43253
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-667, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <496269d12072ecb219826485bdbec70c92a8eef5
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <715c263119fd1b918a9fcbd8a36ea5b604a46324
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d2a0cac10597068567d336e85fa3cbdbe8ca62bf
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e15768e68820142077bbca402d8e902f64ade1b0
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f2f65b28d802a667119147444ec2ae33eebf9a58

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <496269d12072ecb219826485bdbec70c92a8eef5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <715c263119fd1b918a9fcbd8a36ea5b604a46324; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d2a0cac10597068567d336e85fa3cbdbe8ca62bf; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e15768e68820142077bbca402d8e902f64ade1b0; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f2f65b28d802a667119147444ec2ae33eebf9a58

Published CVSS scores

7.5Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-667Improper Locking
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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