# CVE-2026-38821: Memory corruption in openNDS

> An unauthenticated attacker can crash the openNDS daemon or potentially execute code via a heap-based buffer overflow in the captive portal network.

- **Severity:** High 7.1 (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-38821, GHSA-rm65-3jj4-3vcm, UBUNTU-CVE-2026-38821

## What is CVE-2026-38821?

CVE-2026-38821 is a high-severity memory corruption vulnerability in openNDS, published on 28 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A heap-based buffer overflow vulnerability exists in openNDS before 11.0.0 that allows an unauthenticated attacker on the captive portal network to crash the openNDS daemon (denial of service) and potentially achieve remote code execution. This is in http_microhttpd.c.

Weakness: CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-38821?


## How do I fix CVE-2026-38821?

No fix has been published for CVE-2026-38821 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-38821 being exploited?

There is no known exploitation of CVE-2026-38821 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-38821 and fix it if it is affected.

What it is: CVE-2026-38821 is a high-severity memory corruption vulnerability in openNDS, published on 28 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-2026-38821 in the wild and no public exploit code.

Affected product: openNDS. 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-2026-38821/ (Markdown: https://insights.sbomify.com/CVE-2026-38821/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-38821
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-38821
- OSV: https://osv.dev/vulnerability/CVE-2026-38821

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-38821/
Summaries are generated and may contain mistakes; the official description above is the record.