CVE-2026-90813

Deferred Deferred - Pending Action

Incorrect Behavior Order in CosmicStack Labs Mercury Agent

Publication date: 2026-09-14

Last updated on: 2026-09-14

Assigner: VulDB

Description

A vulnerability was detected in cosmicstack-labs mercury-agent up to 1.1.13. Affected is the function checkShellCommand of the file src/capabilities/permissions.ts of the component Shell Command Execution. The manipulation results in incorrect behavior order: validate before canonicalize. The attack may be launched remotely. The exploit is now public and may be used. The project was informed of the problem early through an issue report but has not responded yet.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-14

Last Modified

2026-09-14

Generated

2026-09-15

AI Q&A

2026-09-15

EPSS Evaluated

N/A

NVD

CVE-2026-90813

EUVD

EUVD-2026-77773

Affected Vendors & Products

Vendor	Product	Version / Range
cosmicstack-labs	mercury-agent	to 1.1.13 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-180	The product validates input before it is canonicalized, which prevents the product from detecting data that becomes invalid after the canonicalization step.
CWE-179	The product validates input before applying protection mechanisms that modify the input, which could allow an attacker to bypass the validation via dangerous inputs that only arise after the modification.

Attack-Flow Graph

Executive Summary

This vulnerability affects cosmicstack-labs mercury-agent up to version 1.1.13. It involves a flaw in the function checkShellCommand where validation of shell commands occurs before canonicalization, leading to incorrect behavior. Specifically, the system validates commands like 'head $HOME/secret.txt' as safe by matching against patterns like 'head *' but fails to account for shell variable expansion during execution. This allows attackers to bypass workspace boundaries and access files outside the intended directory.

Detection Guidance

Check if cosmicstack-labs mercury-agent versions 1.1.13 or earlier are installed using package managers like npm or by inspecting the installed package version directly. Look for unusual shell command executions in logs that use variables like $HOME or other shell expansions that bypass workspace boundaries.

Impact Analysis

An attacker could exploit this to read arbitrary local files outside the workspace, including sensitive files like home directory secrets, SSH keys, API keys, and configuration files. The attack can be launched remotely and does not require elevated permissions. Users running affected versions (1.1.13 or earlier) are at risk of unauthorized file disclosure.

Mitigation Strategies

Upgrade cosmicstack-labs mercury-agent to version 1.1.14 or later immediately. If upgrading is not possible, restrict shell command execution capabilities and review all safe-read patterns to ensure they account for shell variable expansions. Disable or limit the use of shell: true in spawn() calls.

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