CVE-2026-90199 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution maintainers, and users of Linux systems with the ntfs3 filesystem driver should be aware of this vulnerability. They should review and apply the patch to the Linux kernel, update the Linux kernel to the latest version, and monitor system logs for potential exploitation attempts. They should also assess exposure and prioritize remediation for affected systems.

Why it matters

The vulnerability in the Linux kernel's ntfs3 filesystem driver could lead to issues when handling malformed on-disk attributes. Defenders should verify patch application, monitor system logs, and assess exposure to prioritize remediation.

• Verify patch application and kernel version updates
• Monitor system logs for potential exploitation attempts
• Assess exposure and prioritize remediation for affected systems

Technical summary

The `mi_enum_attr()` function in the Linux kernel's ntfs3 filesystem driver did not properly validate the end virtual cluster number (evcn) for non-resident attributes. This could lead to issues when handling malformed on-disk attributes. The vulnerability has been resolved with a patch that rejects evcn values outside the valid range, which is determined by the volume's total cluster count. The patch also allows an empty non-resident attribute with svcn == 0 and evcn == -1 (U64_MAX) to pass, as this is a legitimate sentinel value. The fix ensures that the `mi_enum_attr()` function now properly validates evcn values, preventing potential issues with malformed on-disk attributes.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the patch to the Linux kernel
• Update the Linux kernel to the latest version
• Monitor system logs for potential exploitation attempts
• Verify patch application and kernel version updates
• Assess exposure and prioritize remediation for affected systems
• 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 CVE record and NVD entry provide details on the vulnerability, including its description and CVSS score of 7.8. The Linux kernel source code references are also provided. The vulnerability was resolved with a patch that rejects evcn values outside the valid range. The patch was applied to the Linux kernel to fix the issue. The fix allows for proper validation of evcn values, preventing potential issues with malformed on-disk attributes. The CVE record was published on 2026-09-17T17:17:14.790Z and has not been modified since then.

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.