CVE-2026-23067 iommu/io-pgtable-arm: fix size_t signedness bug in unmap path

What is CVE-2026-23067?

CVE-2026-23067 is a medium-severity vulnerability in Linux kernel, published on 4 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

iommu/io-pgtable-arm: fix size_t signedness bug in unmap path

__arm_lpae_unmap() returns size_t but was returning -ENOENT (negative error code) when encountering an unmapped PTE. Since size_t is unsigned, -ENOENT (typically -2) becomes a huge positive value (0xFFFFFFFFFFFFFFFE on 64-bit systems).

This corrupted value propagates through the call chain: __arm_lpae_unmap() returns -ENOENT as size_t -> arm_lpae_unmap_pages() returns it -> __iommu_unmap() adds it to iova address -> iommu_pgsize() triggers BUG_ON due to corrupted iova

This can cause IOVA address overflow in __iommu_unmap() loop and trigger BUG_ON in iommu_pgsize() from invalid address alignment.

Fix by returning 0 instead of -ENOENT. The WARN_ON already signals the error condition, and returning 0 (meaning "nothing unmapped") is the correct semantic for size_t return type. This matches the behavior of other io-pgtable implementations (io-pgtable-arm-v7s, io-pgtable-dart) which return 0 on error conditions.

Weakness: CWE-617

Which versions are affected by CVE-2026-23067?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-23067?

Apply the vendor's patch.

Is CVE-2026-23067 being exploited?

There is no known exploitation of CVE-2026-23067 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-23067, DEBIAN-CVE-2026-23067, GHSA-vjjp-v767-cx96, UBUNTU-CVE-2026-23067.