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Linux Kernel CVE-2026-43253

| EUVDEUVD-2026-27816 HIGH
Improper Locking (CWE-667)
2026-05-06 Linux GHSA-jqx2-5f2v-644h
Amd Information Disclosure Linux Red Hat Suse
High
Disputed · 7.5 NVD
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Severity by source

Sources disagree (Low–High)
NVD PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE
HIGH
qualitative
Red Hat
5.5 LOW
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
Analysis Generated
May 08, 2026 - 13:43 vuln.today
CVSS changed
May 08, 2026 - 13:22 NVD
7.5 (HIGH)
Patch available
May 06, 2026 - 13:32 EUVD
CVE Published
May 06, 2026 - 11:28 nvd
HIGH 7.5

DescriptionCVE.org

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

iommu/amd: move wait_on_sem() out of spinlock

With iommu.strict=1, the existing completion wait path can cause soft lockups under stressed environment, as wait_on_sem() busy-waits under the spinlock with interrupts disabled.

Move the completion wait in iommu_completion_wait() out of the spinlock. wait_on_sem() only polls the hardware-updated cmd_sem and does not require iommu->lock, so holding the lock during the busy wait unnecessarily increases contention and extends the time with interrupts disabled.

AnalysisAI

AMD IOMMU completion wait operations in the Linux kernel can trigger soft lockups under high load when strict mode is enabled (iommu.strict=1). The vulnerability stems from busy-waiting inside a spinlock with interrupts disabled, causing kernel responsiveness issues and potential denial of service on systems with AMD IOMMU hardware. Patches are available across multiple kernel stable branches (6.6.128, 6.12.75, 6.18.16, 6.19.6, 7.0). EPSS score is low (0.02%, 5th percentile) with no confirmed active exploitation or public POC identified at time of analysis.

Technical ContextAI

The AMD IOMMU (Input-Output Memory Management Unit) subsystem in the Linux kernel manages DMA address translation and isolation for AMD processors. When operating in strict mode (iommu.strict=1), the driver enforces synchronous completion waits after IOMMU command submissions to ensure strict ordering guarantees. The vulnerable code path calls wait_on_sem() while holding iommu->lock with interrupts disabled, creating a busy-wait loop that polls hardware-updated completion semaphores. Under high IOMMU command throughput, this design causes excessive spinlock contention and prolonged interrupt-disabled periods, leading to scheduler delays and soft lockup detection. The fix relocates the completion wait outside the critical section, as the semaphore polling does not require lock protection. This affects systems using AMD IOMMU hardware with strict mode enabled, a configuration common in security-sensitive or real-time environments requiring guaranteed DMA isolation ordering.

RemediationAI

Primary remediation is upgrading to patched kernel versions: 6.6.128, 6.12.75, 6.18.16, 6.19.6, or 7.0 depending on your stable branch. Upstream patches are available at the kernel.org git stable repository links provided in CVE references. For systems unable to immediately patch, disable strict IOMMU mode by removing iommu.strict=1 from kernel boot parameters or setting iommu.strict=0, which eliminates the busy-wait condition but reduces DMA isolation ordering guarantees-acceptable for non-security-critical workloads but not recommended for virtualization hosts requiring strict memory isolation. Another workaround is reducing IOMMU command submission rate by limiting concurrent DMA operations, though this degrades I/O performance significantly. Systems not using AMD IOMMU hardware or not running in strict mode are unaffected and require no action. Verify strict mode status with dmesg | grep -i iommu before deciding on workarounds. Consult distribution-specific security advisories for backported patches in enterprise kernels.

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Same technique Information Disclosure

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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7 Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed

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CVE-2026-43253 vulnerability details – vuln.today
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