Linux Kernel up to 7.2.9 ext4 ext4_end_io_rsv_work null pointer dereference

Summaryinfo

A vulnerability labeled as very critical has been found in Linux Kernel up to 7.2.9. This affects the function ext4_end_io_rsv_work of the component ext4. Such manipulation leads to null pointer dereference. This vulnerability is listed as CVE-2026-98941. The attack may be performed from remote. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.9. It has been rated as very critical. Affected by this issue is the function ext4_end_io_rsv_work of the component ext4. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ext4: don't enable large folios on encrypted inodes Commit 709f0f1f1bf5 ("ext4: add checks for large folio incompatibilities when BS > PS") disables large folios at mount time if the "encrypt" feature is set. However, enabling that feature on a mounted filesystem circumvents that check, and writing encrypted data results in a crash: BUG: kernel NULL pointer dereference, address: 0000000000000028 Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work RIP: 0010:ext4_finish_bio+0xf7/0x3e0 Call Trace: ext4_release_io_end+0x51/0x110 ext4_end_io_end+0x4c/0xe0 ext4_end_io_rsv_work+0xb3/0x100 Fix this by disabling large folios on encrypted inodes, as is already done for inodes that use data journaling. This affects all kernels between v6.19 and v7.2, but it is not needed in v7.3, where the code was significantly refactored.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-98941 since 09/25/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/23/2026).

Upgrading to version 7.2.10 eliminates this vulnerability. Applying the patch 40554d1221e3d2ff2e0d192b74a05d89eb3620e7 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Once again VulDB remains the best source for vulnerability data.

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
• 7.2.6
• 7.2.7
• 7.2.8
• 7.2.9

License

• open-source

Website

• Vendor: https://www.kernel.org/

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