CVE-2026-98635 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution maintainers, system administrators responsible for Linux systems, security teams assessing Linux system vulnerability, and operators of Linux-based systems. These individuals should assess exposure and prioritize patching or verification for systems using the affected Linux kernel functionality.

Why it matters

CVE-2026-98635 is a Linux kernel vulnerability that allows out-of-bounds writes during disk zone validation. Linux kernel developers and maintainers, Linux distribution maintainers, system administrators, and security teams should assess exposure and prioritize patching or verification for systems using the affected Linux kernel functionality.

• Potential memory corruption due to out-of-bounds writes.
• Necessity to verify the integrity of disk zone reports.
• Priority to apply patches or updates from Linux.
• Potential impact on system stability and security.

Technical summary

The blk_revalidate_disk_zones function in the Linux kernel does not properly check the index against the zones_cond array size. This can lead to out-of-bounds writes when a device reports more zones than fit within the array. The issue arises from the discrepancy between the zone count stored in unsigned int variables and the actual zone count reported by the device. The vulnerability can be triggered by a device reporting more zones than fit the array, causing blk_zone_set_cond() to write out of bounds. This can lead to potential memory corruption and system instability.

Defensive priority

Apply patches or updates from Linux to address the vulnerability. Assess exposure and prioritize verification for systems using the affected Linux kernel functionality.

Recommended defensive actions

• Apply patches or updates from Linux to address the vulnerability.
• Assess exposure and prioritize verification for systems using the affected Linux kernel functionality.
• Verify the integrity of disk zone reports to prevent potential out-of-bounds writes.
• 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.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. Two source references from git.kernel.org are available, detailing the patches addressing the issue. The Linux kernel vulnerability allows out-of-bounds writes during disk zone validation. The issue arises from the discrepancy between the zone count stored in unsigned int variables and the actual zone count reported by the device. The CVE record was published on 2026-10-18T16:17:16.607Z and has not been modified since then. The NVD entry provides additional information

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.