Linux Kernel up to 6.19.8 io_init_req privilege escalation

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Linux Kernel up to 6.19.8. Impacted is the function io_init_req. The manipulation leads to an unknown weakness. This vulnerability is traded as CVE-2026-43442. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Linux Kernel up to 6.19.8. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: io_uring: fix physical SQE bounds check for SQE_MIXED 128-byte ops When IORING_SETUP_SQE_MIXED is used without IORING_SETUP_NO_SQARRAY, the boundary check for 128-byte SQE operations in io_init_req() validated the logical SQ head position rather than the physical SQE index. The existing check: !(ctx->cached_sq_head & (ctx->sq_entries - 1)) ensures the logical position isn't at the end of the ring, which is correct for NO_SQARRAY rings where physical == logical. However, when sq_array is present, an unprivileged user can remap any logical position to an arbitrary physical index via sq_array. Setting sq_array[N] = sq_entries - 1 places a 128-byte operation at the last physical SQE slot, causing the 128-byte memcpy in io_uring_cmd_sqe_copy() to read 64 bytes past the end of the SQE array. Replace the cached_sq_head alignment check with a direct validation of the physical SQE index, which correctly handles both sq_array and NO_SQARRAY cases.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-43442 since 05/01/2026. 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 05/22/2026).

Upgrading to version 6.19.9 eliminates this vulnerability. Applying the patch 1f794f9bed3e5cf7250a3b4daf112a72ed1513e9/6f02c6b196036dbb6defb4647d8707d29b7fe95b is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. 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

• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

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