Linux Kernel up to 7.2.5 ext4 ext4_meta_trans_blocks allocation of resources

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Linux Kernel up to 7.2.5. This affects the function ext4_meta_trans_blocks of the component ext4. Performing a manipulation results in allocation of resources. This vulnerability is reported as CVE-2026-100073. The attack is possible to be carried out remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Linux Kernel up to 7.2.5. This affects the function ext4_meta_trans_blocks of the component ext4. The manipulation with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. This is going to have an impact on integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-100073 since 09/25/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/25/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch a22464c5df5827e884a5a7d3d8fb03870e5bb6c8/46e8e31771f4f1c5e1cdec37a889a6730e42e9f1 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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