# CVE-2026-123999: ION-DTN 3.6.2-4.2.0 Heap Buffer Overflow via nm_mgr AMP Rendering


- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 9 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** GHSA-gmhw-vmwr-wrxh

## What is CVE-2026-123999?

CVE-2026-123999 is a high-severity vulnerability in nasa-jpl ION-DTN, published on 9 Nov 2026. 

### Official description

NASA JPL ION-DTN 3.6.2 through 4.2.0 contains a heap-based buffer overflow in the Network Management daemon (nm_mgr) string-formatting logic that allows a malicious or misconfigured agent to trigger an out-of-bounds write by sending deeply nested AMP payloads that exceed fixed-size buffer allocations through unbounded strcat operations. Attackers can transmit oversized AMP reports, tables, or macros over the UDP CLA/AMP path or trigger the flaw locally via interactive UI rendering to crash nm_mgr and cause a denial of service halting telemetry collection and operator visibility.

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

## Which versions are affected by CVE-2026-123999?


## How do I fix CVE-2026-123999?

No fix has been published for CVE-2026-123999 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-123999 being exploited?

There is no known exploitation of CVE-2026-123999 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123999 and fix it if it is affected.

What it is: CVE-2026-123999 is a high-severity vulnerability in nasa-jpl ION-DTN, published on 9 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123999 in the wild and no public exploit code.

Affected product: nasa-jpl ION-DTN. 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-2026-123999/ (Markdown: https://insights.sbomify.com/CVE-2026-123999/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123999
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123999
- OSV: https://osv.dev/vulnerability/CVE-2026-123999

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123999/
Summaries are generated and may contain mistakes; the official description above is the record.