Linux kernel btrfs race in sb_write_pointer() with BLKBSZSET
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 1 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
In the Linux kernel btrfs code, sb_write_pointer() reads the superblock from the block device page cache with read_cache_page_gfp() without serializing against block size changes made through BLKBSZSET. This is the same race that commit 3f29d661e568 fixed for the disk super read. Linux from 6.15 is affected. Red Hat rates it Moderate, and CISA has not added it to KEV.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: btrfs: protect sb_write_pointer() with invalidate lock sb_write_pointer() reads the super block from the block device page cache using read_cache_page_gfp(). This has the same race with BLKBSZSET as the one fixed by commit 3f29d661e568 ("btrfs: sync read disk super and set block size"). Take the mapping invalidate lock around read_cache_page_gfp() to serialize the read against block size changes.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Install a fixed kernel: 6.18.53 or 7.2, which take the mapping invalidate lock around read_cache_page_gfp(). Red Hat Enterprise Linux 10 has no fix available yet.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 6.18.53, 7.2
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
Not affected: 6 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-23 Threatist record created from CVE-2026-98907
- 2026-10-23 Alias added: GHSA-2r98-r7qj-j43v
- 2026-10-26 Fix available: Linux/Linux@0 · CNA
- 2026-10-27 Affected versions changed · Red Hat
- 2026-10-27 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
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Sources
- CVE-2026-98907 · CVE Program
- CVE-2026-98907 · NVD
- FIRST EPSS
- GHSA-2r98-r7qj-j43v · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98907 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences