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

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/nasa-jpl/ION-DTN/releases/tag/ion-open-source-4.2.1-a.2

## Affected products and versions

- nasa-jpl / ION-DTN (nasa-jpl/ION-DTN): ≥ 3.6.2; ≤ 4.2.0 (affected, semver); 4.2.1-a.2 (unaffected, custom). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.7 (high); 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; source: CNA: VulnCheck

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-122

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/nasa-jpl/ION-DTN/security/advisories/GHSA-gmhw-vmwr-wrxh (CNA: VulnCheck; vendor-advisory)

- https://github.com/nasa-jpl/ION-DTN/releases/tag/ion-open-source-4.2.1-a.2 (CNA: VulnCheck; release-notes, patch)

- https://www.vulncheck.com/advisories/ion-dtn-heap-buffer-overflow-via-nm-mgr-amp-rendering (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-123999; retrieved 2026-11-09; source updated 2026-11-09

Revision: 22e0e7d3fd1fd3303c6f6c34cd362e39f0d11fd75c119d2fd72b00b1c04a87ff

Canonical: https://y2.dev/cve/CVE-2026-123999

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