CVE-2026-100073
Received Received - Intake

ext4 Filesystem Transaction Overflow Vulnerability

Vulnerability report for CVE-2026-100073, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-25

Last updated on: 2026-09-25

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix transaction overflow during writeback Commit 95ad8ee45cdb ("ext4: correct the reserved credits for extent conversion") was correct to note that we need to reserve enough credits for all extents possibly underlying a large folio. However it was too eager to reduce the number of reserved credits. Extent conversion may not only need to touch several leaf extent blocks, it may also need to split extents - for example a single large unwritten extent may need to be split into many small written ones in case of sparse folio dirtying. This can thus result not only in extent leaf modifications but also in a need to allocate new extent tree nodes. As a result the reserved transaction credits were not sufficient in some corner cases. Use ext4_meta_trans_blocks() for correct upper bound credit estimate.

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Meta Information

Published
2026-09-25
Last Modified
2026-09-25
Generated
2026-09-25
AI Q&A
2026-09-25
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a transaction overflow during writeback in the ext4 filesystem. It occurs when reserved credits for extent conversion are insufficient. Specifically, splitting large unwritten extents into smaller written ones during sparse folio dirtying may require additional extent tree node allocations, exceeding the initially reserved transaction credits.

Detection Guidance

This vulnerability is specific to the Linux kernel's ext4 filesystem and requires kernel-level detection. Check your kernel version with 'uname -r' and compare against patched versions. Monitor for filesystem corruption or writeback failures during heavy I/O operations.

Impact Analysis

This vulnerability could lead to filesystem corruption or data loss if the kernel fails to handle write operations properly due to insufficient transaction credits. It may cause system crashes, application errors, or unexpected behavior during disk writes, particularly with large or sparse files.

Mitigation Strategies

Apply the latest kernel patches from your distribution. If immediate patching isn't possible, reduce filesystem write operations and monitor for ext4 errors in system logs. Consider using alternative filesystems temporarily if the risk is high.

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