CVE-2026-43253 iommu/amd: move wait_on_sem() out of spinlock

What is CVE-2026-43253?

CVE-2026-43253 is a high-severity denial of service vulnerability in Linux kernel, published on 6 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-667, CWE-833

Which versions are affected by CVE-2026-43253?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-43253?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-43253 being exploited?

There is no known exploitation of CVE-2026-43253 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-43253, DEBIAN-CVE-2026-43253, GHSA-jqx2-5f2v-644h, ROOT-OS-DEBIAN-11-CVE-2026-43253, ROOT-OS-DEBIAN-12-CVE-2026-43253, ROOT-OS-UBUNTU-2204-CVE-2026-43253 and 2 more.