CVE-2026-91988
Received Received - Intake

HTTP MCP Server-Registry Cleartext Credential Exposure in Atomic Agents Stack

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: VulnCheck

Description
atomic-agents-stack before 1.1.0 accepts cleartext HTTP schemes in the HTTP MCP server-registry backend factory, allowing network man-in-the-middle attackers to rewrite catalog responses. Attackers can inject arbitrary command and argument values that are spawned as local subprocesses by MCPClientPool to achieve code execution on the agent host.

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Meta Information

Published
2026-09-15
Last Modified
2026-09-15
Generated
2026-09-15
AI Q&A
2026-09-15
EPSS Evaluated
N/A
NVD
CVE-2026-91988
EUVD
EUVD-2026-78659

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-319 The product transmits sensitive or security-critical data in cleartext in a communication channel that can be sniffed by unauthorized actors.

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Executive Summary

This vulnerability affects atomic-agents-stack versions before 1.1.0. It allows network attackers to intercept cleartext HTTP traffic and modify catalog responses by injecting arbitrary commands. These commands are then executed as local subprocesses by MCPClientPool, leading to remote code execution on the agent host without requiring LLM interaction.

Detection Guidance

To detect this vulnerability, check if your atomic-agents-stack version is below 1.1.0. Inspect network traffic for cleartext HTTP MCP catalog requests. Look for unexpected command or argument values in catalog responses. Use commands like 'curl -v http://<server>/mcp/catalog' to check for HTTP usage.

Impact Analysis

An attacker could execute arbitrary code on your system by intercepting HTTP traffic and modifying catalog entries. This could lead to full system compromise, data theft, or further network infiltration. The attack does not require user interaction and can happen silently in the background.

Compliance Impact

This vulnerability could lead to unauthorized code execution and data breaches, violating GDPR's integrity and confidentiality requirements and HIPAA's safeguards for protected health information. It may result in non-compliance due to potential data exposure and lack of integrity controls in data transmission.

Mitigation Strategies

Immediately upgrade atomic-agents-stack to version 1.1.0 or later. Disable HTTP MCP server-registry backend if not required. Enable HTTPS for all MCP communications. Implement network monitoring to detect unauthorized command execution attempts.

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