# CVE-2025-39958: iommu/s390: Make attach succeed when the device was surprise removed > A flaw in the Linux kernel's s390 IOMMU driver causes a kernel warning and potential instability when attaching a surprise-removed PCI device. - **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 9 Oct 2025 - **Updated:** 21 Oct 2026 - **Also known as:** BELL-CVE-2025-39958, DEBIAN-CVE-2025-39958, GHSA-p5vh-p63c-cg4v, ROOT-OS-DEBIAN-13-CVE-2025-39958, ROOT-OS-UBUNTU-2204-CVE-2025-39958, ROOT-OS-UBUNTU-2404-CVE-2025-39958, UBUNTU-CVE-2025-39958 ## What is CVE-2025-39958? CVE-2025-39958 is a high-severity denial of service vulnerability in Linux kernel, published on 9 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: iommu/s390: Make attach succeed when the device was surprise removed When a PCI device is removed with surprise hotplug, there may still be attempts to attach the device to the default domain as part of tear down via (__iommu_release_dma_ownership()), or because the removal happens during probe (__iommu_probe_device()). In both cases zpci_register_ioat() fails with a cc value indicating that the device handle is invalid. This is because the device is no longer part of the instance as far as the hypervisor is concerned. Currently this leads to an error return and s390_iommu_attach_device() fails. This triggers the WARN_ON() in __iommu_group_set_domain_nofail() because attaching to the default domain must never fail. With the device fenced by the hypervisor no DMAs to or from memory are possible and the IOMMU translations have no effect. Proceed as if the registration was successful and let the hotplug event handling clean up the device. This is similar to how devices in the error state are handled since commit 59bbf596791b ("iommu/s390: Make attach succeed even if the device is in error state") except that for removal the domain will not be registered later. This approach was also previously discussed at the link. Handle both cases, error state and removal, in a helper which checks if the error needs to be propagated or ignored. Avoid magic number condition codes by using the pre-existing, but never used, defines for PCI load/store condition codes and rename them to reflect that they apply to all PCI instructions. ## Which versions are affected by CVE-2025-39958? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2025-39958? Apply the vendor's patch. ## Is CVE-2025-39958 being exploited? There is no known exploitation of CVE-2025-39958 in the wild and no public exploit code. ## Other vulnerabilities in Linux kernel - [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild) - [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild) - [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild) - [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild) - [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2025-39958 and fix it if it is affected. What it is: CVE-2025-39958 is a high-severity denial of service vulnerability in Linux kernel, published on 9 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2025-39958 in the wild and no public exploit code. Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2025-39958/ (Markdown: https://insights.sbomify.com/CVE-2025-39958/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39958 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39958 - OSV: https://osv.dev/vulnerability/CVE-2025-39958 --- From sbomify Insights: https://insights.sbomify.com/CVE-2025-39958/ Summaries are generated and may contain mistakes; the official description above is the record.