High

Out-of-bounds read in Linux kernel io_uring fixed buffer import

IdentifiersCVE-2026-43006CWE-125· Out-of-bounds Read

CVE-2026-43006 is an out-of-bounds read vulnerability in the Linux kernel io_uring resource handling code for fixed buffers. The flaw arises because validate_fixed_range() permits a buffer address positioned exactly at the end of a registered buffer region when the requested length is zero. This occurs due to a strict greater-than boundary check. Subsequently, io_import_fixed() computes an offset equal to the registered buffer length and proceeds into bio_vec traversal logic despite there being no data to import. The bvec skip logic can then advance past the final bio_vec entry and read bv_offset from memory beyond the allocated slab object, resulting in a slab out-of-bounds read. The fix rejects zero-length fixed buffer imports by returning early from io_import_fixed(), preventing traversal of the bvec array when no transfer should occur.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can trigger an out-of-bounds read in kernel memory, causing kernel memory safety violations and potentially leading to a kernel crash or other denial-of-service condition. Because the read occurs in kernel context and accesses memory beyond the intended slab allocation, there is also a risk of unintended exposure of adjacent kernel memory contents, although the available information does not confirm practical information disclosure beyond the out-of-bounds read itself.

Mitigation

If you can’t patch tonight, do this now.

Until patched kernels can be deployed, reduce exposure by restricting access to io_uring-capable interfaces to trusted local users and workloads only, and by minimizing the ability of untrusted code to register and use fixed buffers with io_uring. Where operationally feasible, disable or constrain untrusted local execution paths such as multi-tenant shell access, untrusted containers, or sandbox escapes that could reach the vulnerable kernel interface. Mitigation is limited because the flaw is in kernel logic and is best addressed through patching.

Remediation

Patch, then assume compromise.

Apply a Linux kernel update that includes the fix for CVE-2026-43006. The corrected behavior rejects zero-length fixed buffer imports in io_uring by returning early from io_import_fixed() before any bio_vec traversal occurs. On Red Hat Enterprise Linux 10 and related channels, install the kernel update provided in RHSA-2026:21557 or a later kernel package containing the fix, and reboot the system for the updated kernel to take effect.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

LinuxLinux Kerneloperating_system

Rocky LinuxRocky Linuxoperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

2 SOURCESView more in app

redhat accessNews

May 28, 2026

RHSA-2026:21557 - Security Advisory - Red Hat Customer Portal

A Linux kernel io_uring resource-management vulnerability involving acceptance of zero-length fixed buffer imports.

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Exposure mapping

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity