CVE-2026-45018Public exploitNetwork attack vector

Unauthenticated RCE via unchecked MCP command arguments

Published Aug 25, 2026 · Updated Aug 25, 2026

Command injection in Chainlit 2.4.0rc0 through 2.11.1 allows remote attackers to execute OS commands through an enabled MCP stdio endpoint. The validate_mcp_command() function checks only the executable name, then passes attacker-controlled arguments to StdioServerParameters for subprocess creation. Exploitation requires features.mcp.enabled to be true; no authentication is required, and commands run with the Chainlit process privileges.

CVSS severity9.8
Critical
EPSS probability0.65%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Chainlit 2.4.0rc0 through 2.11.1 allows remote attackers to execute OS commands through an enabled MCP stdio endpoint. The validate_mcp_command() function checks only the executable name, then passes attacker-controlled arguments to StdioServerParameters for subprocess creation. Exploitation requires features.mcp.enabled to be true; no authentication is required, and commands run with the Chainlit process privileges.

The record

CVE
CVE-2026-45018
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
Chainlit
Product
Chainlit
Classifications
CWE-78, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.4.0rc0, < 2.12.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Chainlit · Chainlitversion=>= 2.4.0rc0, < 2.12.0

Published CVSS scores

9.8GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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