# CVE-2026-46115: block: add pgmap check to biovec_phys_mergeable

> Improper merging of physically contiguous block vectors from different device memory maps can lead to incorrect memory access or data corruption in the Linux kernel.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-88812, BELL-CVE-2026-46115, DEBIAN-CVE-2026-46115, GHSA-3588-2x8w-w62r, ROOT-OS-UBUNTU-2404-CVE-2026-46115, UBUNTU-CVE-2026-46115

## What is CVE-2026-46115?

CVE-2026-46115 is a critical vulnerability in Linux kernel, published on 28 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

block: add pgmap check to biovec_phys_mergeable

biovec_phys_mergeable() is used by the request merge, DMA mapping,
and integrity merge paths to decide if two physically contiguous
bvec segments can be coalesced into one. It currently has no check
for whether the segments belong to different dev_pagemaps.

When zone device memory is registered in multiple chunks, each chunk
gets its own dev_pagemap. A single bio can legitimately contain
bvecs from different pgmaps -- iov_iter_extract_bvecs() breaks at
pgmap boundaries but the outer loop in bio_iov_iter_get_pages()
continues filling the same bio. If such bvecs are physically
contiguous, biovec_phys_mergeable() will coalesce them, making it
impossible to recover the correct pgmap for the merged segment
via page_pgmap().

Add a zone_device_pages_have_same_pgmap() check to prevent merging
bvec segments that span different pgmaps.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-46115?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46115?

Apply the vendor's patch.

## Is CVE-2026-46115 being exploited?

There is no known exploitation of CVE-2026-46115 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46115 and fix it if it is affected.

What it is: CVE-2026-46115 is a critical vulnerability in Linux kernel, published on 28 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46115 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-46115/ (Markdown: https://insights.sbomify.com/CVE-2026-46115/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46115
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46115
- OSV: https://osv.dev/vulnerability/CVE-2026-46115

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46115/
Summaries are generated and may contain mistakes; the official description above is the record.