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Fencer Vulns
medium 5.5

CVE-2026-23067 json

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

published 2026-02-04 9 mo ago modified 2026-11-05 3 d ago also EUVD-2026-5477

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 6.18.8, 6.19
  • linux Debian 14 6.18.8-1

debian advisories DEBIAN-CVE-2026-23067

  • linux-gcp-6.17 Ubuntu 24.04 LTS 6.17.0-1021.24~24.04.1
  • linux-hwe-6.17 Ubuntu 24.04 LTS 6.17.0-41.41~24.04.1
  • linux-oem-6.17 Ubuntu 24.04 LTS 6.17.0-1030.30
  • linux-azure-6.17 Ubuntu 24.04 LTS 6.17.0-1021.21~24.04.1
  • linux-nvidia-6.17 Ubuntu 24.04 LTS 6.17.0-1031.31
  • linux-oracle-6.17 Ubuntu 24.04 LTS 6.17.0-1019.19~24.04.3
  • linux-realtime-6.17 Ubuntu Pro Realtime 24.04 LTS 6.17.0-1018.20~24.04.1

ubuntu advisories UBUNTU-CVE-2026-23067

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-23067 updated cvss 5.5

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

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: no fix available
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 d ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

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