# CVE-2026-23067: linux: In the Linux kernel, the following vulnerability has been resolved:  iommu/io-pgtable-arm: fix size_t signedness bug...

CVE-2026-23067 is fixed in linux on 1 platform by DEBIAN-CVE-2026-23067 (version 6.18.8-1), released February 4, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-23067
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 4, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.18.8-1 | [DEBIAN-CVE-2026-23067](https://patchblox.com/security/data/fix/linux/debian-cve-2026-23067.md) | Feb 4, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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