Summary
In the Linux kernel, the following vulnerability has been resolved: iommu/s390: Make attach...
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.
Impact
CVE-2025-39958 has a CVSS score of 7.8 (High). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-39958? CVE-2025-39958 is a high-severity security vulnerability. No fixed version is listed yet.
- How severe is CVE-2025-39958? CVE-2025-39958 has a CVSS score of 7.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-39958? No fixed version is listed for CVE-2025-39958 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-39958 exploitable, and should I be worried? Whether CVE-2025-39958 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-39958 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.