# CVE-2026-68172: arm64: make huge_ptep_get handled unaligned addresses

> A local attacker can trigger a kernel panic by causing the arm64 huge_ptep_get function to dereference an invalid pointer when handling unaligned addresses.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-68172, DEBIAN-CVE-2026-68172, GHSA-mc2f-cm9p-679q, UBUNTU-CVE-2026-68172

## What is CVE-2026-68172?

CVE-2026-68172 is a high-severity vulnerability in Linux, published on 10 Aug 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:

arm64: make huge_ptep_get handled unaligned addresses

huge_ptep_get() can be handed a virtual address pointing to the middle
of a contpmd/contpte mapped hugetlb folio (examples of callers are
pagemap_hugetlb_range, page_mapped_in_vma).

The arm64 helper rewalks the pgtables in find_num_contig to answer
whether the huge pte we have maps a contpmd or a contpte hugetlb folio,
and returns CONT_PMDS or CONT_PTES, so that it can collect a/d bits over
the contiguous ptes. We can falsely return CONT_PTES instead of
CONT_PMDS if the addr is not aligned. On systems where CONT_PTES !=
CONT_PMDS (meaning page size is 16K), we could collect excess A/D bit
state, meaning extra work for the kernel. Even worse, we may iterate
beyond the PTE table and dereference a garbage ptep pointer to access
physical memory we don't own. Since the ptep pointer is a linear map
address, we may run off the end of the linear map or into a hole,
dereference a VA not mapped into the kernel pgtables and cause kernel
panic.

Fix this by aligning the pmdp pointer down to a contpmd base before
checking equality with the passed huge pte pointer, to correctly answer
whether the huge pte is the base of a contpmd block.

## Which versions are affected by CVE-2026-68172?


## How do I fix CVE-2026-68172?

Apply the vendor's patch.

## Is CVE-2026-68172 being exploited?

There is no known exploitation of CVE-2026-68172 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68172 and fix it if it is affected.

What it is: CVE-2026-68172 is a high-severity vulnerability in Linux, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-68172 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-68172/ (Markdown: https://insights.sbomify.com/CVE-2026-68172/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68172
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68172
- OSV: https://osv.dev/vulnerability/CVE-2026-68172

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68172/
Summaries are generated and may contain mistakes; the official description above is the record.