Azure linux: A vulnerability in the Linux kernel ext4 filesystem code could leave a stale unwritten extent in the extent status tree after certain block… (CVE-2026-45892)
A vulnerability in the Linux kernel ext4 filesystem code could leave a stale unwritten extent in the extent status tree after certain block splitting and zeroing operations. This occurs when ext4_split_extent() attempts to split an unwritten extent with specific flags set but fails partially due to lack of space, resulting in inconsistent extent status caching. The issue has been fixed by ensuring the extent status entry is always cached after zeroing out the second part of the extent.
AI Analysis
Technical Summary
The vulnerability involves the ext4 filesystem in the Linux kernel where, during splitting of an unwritten extent and converting it to initialized, a stale unwritten extent can remain in the extent status tree. Specifically, when ext4_split_extent() tries to split an extent with EXT4_EXT_MAY_ZEROOUT and EXT4_EXT_DATA_VALID2 flags, failure to split due to temporary lack of space leads to zeroing out part of the extent but leaving the entire extent marked as unwritten. Subsequent splitting and block mapping operations update the on-disk extent and extent status tree inconsistently, leaving stale unwritten extents in the status tree. The fix ensures that extent status entries are always cached after zeroing out the second part, preventing stale entries.
Potential Impact
This vulnerability can cause inconsistencies in the ext4 extent status tree, potentially leading to data integrity issues or filesystem corruption. The CVSS vector indicates no confidentiality or integrity impact but a high availability impact, meaning the vulnerability could cause denial of service or system instability related to filesystem operations.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch links or official fix information is provided, users should monitor the Microsoft Security Response Center advisory for updates and apply any forthcoming fixes promptly.
Azure linux: A vulnerability in the Linux kernel ext4 filesystem code could leave a stale unwritten extent in the extent status tree after certain block… (CVE-2026-45892)
Description
A vulnerability in the Linux kernel ext4 filesystem code could leave a stale unwritten extent in the extent status tree after certain block splitting and zeroing operations. This occurs when ext4_split_extent() attempts to split an unwritten extent with specific flags set but fails partially due to lack of space, resulting in inconsistent extent status caching. The issue has been fixed by ensuring the extent status entry is always cached after zeroing out the second part of the extent.
CVSS v3.1
Score 5.5medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability involves the ext4 filesystem in the Linux kernel where, during splitting of an unwritten extent and converting it to initialized, a stale unwritten extent can remain in the extent status tree. Specifically, when ext4_split_extent() tries to split an extent with EXT4_EXT_MAY_ZEROOUT and EXT4_EXT_DATA_VALID2 flags, failure to split due to temporary lack of space leads to zeroing out part of the extent but leaving the entire extent marked as unwritten. Subsequent splitting and block mapping operations update the on-disk extent and extent status tree inconsistently, leaving stale unwritten extents in the status tree. The fix ensures that extent status entries are always cached after zeroing out the second part, preventing stale entries.
Potential Impact
This vulnerability can cause inconsistencies in the ext4 extent status tree, potentially leading to data integrity issues or filesystem corruption. The CVSS vector indicates no confidentiality or integrity impact but a high availability impact, meaning the vulnerability could cause denial of service or system instability related to filesystem operations.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch links or official fix information is provided, users should monitor the Microsoft Security Response Center advisory for updates and apply any forthcoming fixes promptly.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_vex
- Csaf Version
- 2.0
- Publisher
- Microsoft Security Response Center
- Advisory Id
- msrc_CVE-2026-45892
- Cve Count
- 1
- Additional Cves
- []
- Cvss Version
- 3.1
Threat ID: 6a18ab78e29bf47b50288d0d
Added to database: 05/28/2026, 20:54:16 UTC
Last enriched: 06/26/2026, 23:38:46 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 70
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