# CVE-2026-57843: NetBSD mm_open() PK_KMEM Flag Kernel Pointer Information Disclosure

> Unprivileged local users can leak kernel virtual addresses via world-accessible devices, bypassing obfuscation mechanisms to read sensitive kernel structures.

- **Severity:** Medium 6.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **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:** No
- **Published:** 11 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-p59p-jjhh-5885

## What is CVE-2026-57843?

CVE-2026-57843 is a medium-severity vulnerability in The NetBSD Foundation NetBSD, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

NetBSD contains an information disclosure vulnerability in mm_open() within sys/dev/mm.c that allows unprivileged local users to obtain real kernel virtual addresses by opening world-accessible devices such as /dev/null or /dev/zero, which incorrectly receive the PK_KMEM process flag. Attackers can exploit this misconfigured flag to bypass the CANSEE_KPTR obfuscation mechanism and read kernel virtual addresses for sensitive kernel structures including struct proc, kauth_cred, filedesc, and vmspace via sysctl KERN_PROC queries.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2026-57843?


## How do I fix CVE-2026-57843?

No fix has been published for CVE-2026-57843 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-57843 being exploited?

There is no known exploitation of CVE-2026-57843 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-57843 and fix it if it is affected.

What it is: CVE-2026-57843 is a medium-severity vulnerability in The NetBSD Foundation NetBSD, published on 11 Sep 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-2026-57843 in the wild and no public exploit code.

Affected product: The NetBSD Foundation NetBSD. 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-2026-57843/ (Markdown: https://insights.sbomify.com/CVE-2026-57843/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57843
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57843
- OSV: https://osv.dev/vulnerability/CVE-2026-57843

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-57843/
Summaries are generated and may contain mistakes; the official description above is the record.