# CVE-2026-74524: riscv: mm: Fix out-of-bounds page-table walk during memory hot-remove

> A memory hot-remove flaw in the RISC-V Linux kernel allows out-of-bounds page-table walks, potentially causing system crashes or arbitrary code execution.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74524, DEBIAN-CVE-2026-74524, GHSA-273p-44hj-2v3c, UBUNTU-CVE-2026-74524

## What is CVE-2026-74524?

CVE-2026-74524 is a memory corruption vulnerability in Linux, published on 15 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:

riscv: mm: Fix out-of-bounds page-table walk during memory hot-remove

remove_pud_mapping() and remove_p4d_mapping() obtain a child table base
with pud_offset(p4dp, 0) and p4d_offset(pgd, 0), then add the index for
addr.

RISC-V folds page-table levels at runtime. When a level is folded, its
offset helper returns the parent entry itself, but the index can still be
nonzero. Adding it walks past the parent table. Sv48 folds P4D, while Sv39
folds both P4D and PUD, so memory hot-remove can descend into unrelated
memory and pass an invalid page to __free_pages(). This can trigger:

  kernel BUG at include/linux/mm.h:1810!
  VM_BUG_ON_PAGE(page_ref_count(page) == 0)
  arch_remove_memory+0x1e/0x5c
  try_remove_memory+0x15e/0x200
  remove_memory+0x24/0x3c

Only add the index when the corresponding page-table level is enabled,
matching p4d_offset() and pud_offset().

## Which versions are affected by CVE-2026-74524?


## How do I fix CVE-2026-74524?

Apply the vendor's patch.

## Is CVE-2026-74524 being exploited?

There is no known exploitation of CVE-2026-74524 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74524 and fix it if it is affected.

What it is: CVE-2026-74524 is a memory corruption vulnerability in Linux, published on 15 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-2026-74524 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-2026-74524/ (Markdown: https://insights.sbomify.com/CVE-2026-74524/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74524
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74524
- OSV: https://osv.dev/vulnerability/CVE-2026-74524

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74524/
Summaries are generated and may contain mistakes; the official description above is the record.