# CVE-2026-46020: mm/damon/core: validate damos_quota_goal->nid for node_mem_{used,free}_bp

> Privileged users can trigger an out-of-bounds memory access and kernel crash via DAMON sysfs interface due to missing node ID validation.

- **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:** 27 May 2026
- **Updated:** 14 Jun 2026
- **Also known as:** BELL-CVE-2026-46020, DEBIAN-CVE-2026-46020, GHSA-qpc9-3gvw-7vfq, UBUNTU-CVE-2026-46020

## What is CVE-2026-46020?

CVE-2026-46020 is a high-severity memory corruption vulnerability in Linux kernel, published on 27 May 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:

mm/damon/core: validate damos_quota_goal->nid for node_mem_{used,free}_bp

Patch series "mm/damon/core: validate damos_quota_goal->nid".

node_mem[cg]_{used,free}_bp DAMOS quota goals receive the node id.  The
node id is used for si_meminfo_node() and NODE_DATA() without proper
validation.  As a result, privileged users can trigger an out of bounds
memory access using DAMON_SYSFS.  Fix the issues.

The issue was originally reported [1] with a fix by another author.  The
original author announced [2] that they will stop working including the
fix that was still in the review stage.  Hence I'm restarting this.

This patch (of 2):

Users can set damos_quota_goal->nid with arbitrary value for
node_mem_{used,free}_bp.  But DAMON core is using those for
si_meminfo_node() without the validation of the value.  This can result in
out of bounds memory access.  The issue can actually triggered using DAMON
user-space tool (damo), like below.

    $ sudo ./damo start --damos_action stat \
    	--damos_quota_goal node_mem_used_bp 50% -1 \
    	--damos_quota_interval 1s
    $ sudo dmesg
    [...]
    [   65.565986] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000098

Fix this issue by adding the validation of the given node.  If an invalid
node id is given, it returns 0% for used memory ratio, and 100% for free
memory ratio.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-46020?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46020?

Apply the vendor's patch.

## Is CVE-2026-46020 being exploited?

There is no known exploitation of CVE-2026-46020 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-2026-46020 and fix it if it is affected.

What it is: CVE-2026-46020 is a high-severity memory corruption vulnerability in Linux kernel, published on 27 May 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-2026-46020 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-2026-46020/ (Markdown: https://insights.sbomify.com/CVE-2026-46020/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46020
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46020
- OSV: https://osv.dev/vulnerability/CVE-2026-46020

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46020/
Summaries are generated and may contain mistakes; the official description above is the record.