CVE-2026-80807 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, users of the nilfs2 file system, and administrators of systems using Linux with nilfs2 should verify their kernel versions, review nilfs2 configurations, and apply patches or mitigations as available to prevent potential list corruption due to invalid block index parameters. Additionally, security teams and vulnerability management teams should review the vulnerability and assess the impact on their systems and take

Why it matters

A vulnerability in the Linux kernel's nilfs2 file system has been addressed, which could lead to list corruption due to invalid block index parameters. Defenders should verify Linux kernel versions, review nilfs2 configurations, and apply patches or mitigations as available.

• Verify Linux kernel versions for exposure to prevent potential list corruption
• Review and update nilfs2 file system configurations to ensure valid block index parameters

Technical summary

The GC ioctl in the Linux kernel's nilfs2 file system did not validate block index parameters, potentially leading to list corruption. A patch has been applied to check the ranges of 'vd_offset' and 'vd_vblocknr' in the nilfs_vdesc structure, preventing the insertion of a page/folio with an invalid page index of ULONG_MAX. This patch addresses the issue by ensuring that the page index is within a valid range, thereby preventing duplicate processing of dirty buffers and list corruption. The patch was developed based on the analysis of the vulnerability and the root cause of the issue.

Defensive priority

Verify Linux kernel versions and nilfs2 file system configurations for exposure; apply patches or mitigations as available.

Recommended defensive actions

• Verify Linux kernel versions for exposure
• Review nilfs2 file system configurations
• Apply patches or mitigations as available
• Review compensating controls for exposed systems
• Check relevant monitoring, detection, and logs for exposed assets
• 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 issue is caused by the GC ioctl's lack of range checks on parameters determining the page index, allowing for artificially crafted requests to insert a page/folio with a page index of ULONG_MAX into the page cache.

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.