Quick answers
- Is CVE-2026-121508 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-121508 being exploited in the wild.
- How severe is CVE-2026-121508?
- Medium severity, with a CVSS score of 5.9, published 3 November 2026.
- Which products and versions are affected?
- D3TN µD3TN.
- Is there a fix for CVE-2026-121508?
- No fixed version is recorded yet. Restrict access to the AAP 2.0 dispatcher control interface to trusted hosts. Limit incoming BPv6 bundles to trusted peers or networks to reduce exposure to malformed fragmentation requests. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-121508 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-121508?
- Check whether you run D3TN µD3TN. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
Restrict access to the AAP 2.0 dispatcher control interface to trusted hosts. Limit incoming BPv6 bundles to trusted peers or networks to reduce exposure to malformed fragmentation requests.
Technical details
A use-after-free and double-free vulnerability exists in the BPv6 fragmenter cleanup logic in components/bundle6/fragment.c. When a block duplication fails during fragmentation, the cleanup attempts to restore the payload entry by writing through a cursor that has already advanced past it, forming a cycle in the block list. bundle_free then traverses this cycle and frees the same node twice. The attack requires a specially crafted BPv6 bundle with a payload block followed by a MUST_BE_REPLICATED block, combined with an allocation failure during fragmentation.
Affected products
- D3TN µD3TN
Timeline
- 2026-11-03: disclosed