CVE-2026-97487

Received Received - Intake

JFS Filesystem Blocksize Handling Failure

Publication date: 2026-09-24

Last updated on: 2026-10-03

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: jfs: handle set_blocksize failures jfs uses buffer_heads, which don't handle block size > PAGE_SIZE well. Without this, mounting we will hit the BUG_ON(offset >= folio_size(folio)); in folio_set_bh on the first __bread_gfp call.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-24

Last Modified

2026-10-03

Generated

2026-10-15

AI Q&A

2026-09-25

EPSS Evaluated

2026-10-13

NVD

CVE-2026-97487

EUVD

EUVD-2026-86085

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel relates to the JFS (Journaled File System) failing to handle block size changes properly. The kernel uses buffer_heads which do not support block sizes larger than the system's page size. This can lead to a kernel bug when mounting a filesystem, triggering a BUG_ON assertion failure in folio_set_bh during the first __bread_gfp call.

Detection Guidance

This vulnerability is specific to the JFS filesystem in the Linux kernel and may cause filesystem corruption or crashes when mounting volumes with block sizes larger than PAGE_SIZE. Detection involves checking kernel logs for mount failures or BUG_ON errors related to folio_set_bh. Monitor logs with: dmesg | grep -i 'jfs\|folio_set_bh\|BUG_ON' and check filesystem mount attempts with mount -v.

Impact Analysis

If you use a Linux system with JFS filesystem and attempt to mount a filesystem with a block size larger than the system's page size, the kernel may crash due to the BUG_ON assertion. This could result in a denial of service, system instability, or potential data corruption.

Compliance Impact

This vulnerability affects systems using the JFS filesystem in the Linux kernel, potentially causing crashes during filesystem operations. It does not directly impact compliance with GDPR, HIPAA, or similar standards, as those focus on data protection and privacy rather than filesystem stability.

Mitigation Strategies

Immediate mitigation involves avoiding mounting JFS filesystems with block sizes larger than PAGE_SIZE. Update the Linux kernel to the patched version. If using JFS is necessary, ensure block sizes are set to PAGE_SIZE or smaller. Monitor kernel updates from your distribution for fixes.

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