CVE-2026-89441 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux-based systems that utilize the mmc: via-sdmmc module. These individuals should review and apply the patch to ensure the security and stability of the system. They should also verify the cancellation of card-detect work and finish_bh_work, and ensure the device interrupt is disabled and the IRQ is freed properly.

Why it matters

This vulnerability requires attention from Linux kernel developers, maintainers, and users of Linux-based systems that utilize the mmc: via-sdmmc module. The use-after-free vulnerability can lead to system crashes, instability, or potential elevation of privileges. It is essential to review and apply the patch to ensure the security and stability of the system.

• Potential system crashes or instability due to use-after-free vulnerability
• Possible elevation of privileges or unauthorized access
• Required verification of patch application and system vulnerability

Technical summary

The Linux kernel's mmc: via-sdmmc module has a use-after-free vulnerability. When the device interrupt is disabled and the IRQ is freed, new card-detect work can still run, accessing freed memory. The issue was resolved by canceling card-detect work after freeing the IRQ and before canceling finish_bh_work. This vulnerability affects Linux kernel developers, maintainers, and users of Linux-based systems that utilize the mmc: via-sdmmc module. The patch was applied to the Linux kernel's mmc: via-sdmmc module to resolve the issue.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the patch to the Linux kernel's mmc: via-sdmmc module
• Ensure the device interrupt is disabled and the IRQ is freed properly
• Verify the cancellation of card-detect work and finish_bh_work
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The issue was found by an in-house static analysis tool and confirmed by manual code review. The CVE record and NVD entry provide details on the vulnerability. The vulnerability affects Linux kernel developers, maintainers, and users of Linux-based systems that utilize the mmc: via-sdmmc module. The patch was applied to the Linux kernel's mmc: via-sdmmc module to resolve the issue.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.