{"apiVersion":"1.0","identifier":"CVE-2026-45018","description":"Chainlit is a Python framework for building production-ready conversational AI applications. From 2.4.0rc0 until 2.12.0, Chainlit deployments with features.mcp.enabled set to true in .chainlit/config.toml expose the POST /mcp endpoint without requiring authentication. For stdio transport, the endpoint accepts a user-controlled fullCommand string. The validate_mcp_command() function in backend/chainlit/mcp.py checks only the executable name against config.features.mcp.stdio.allowed_executables and passes unchecked arguments to StdioServerParameters in backend/chainlit/server.py. Because npx supports the -c argument, an attacker can execute arbitrary shell commands with the privileges of the Chainlit process. If allowed_executables is unset, its None default is treated as allowing every executable. This issue is fixed in version 2.12.0.","publishedAt":"2026-08-25T20:16:55","lastModifiedAt":"2026-08-25T20:16:55","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-45018","cvssScore":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","epssProbability":0.00653,"riskScore":1.04,"affectedProduct":"Chainlit","affectedVersions":">=2.4.0rc0,<2.12.0","vulnerabilityType":"Library","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-45018","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-45018","en":"https://www.redsauce.net/en/cves/CVE-2026-45018","fr":"https://www.redsauce.net/fr/cves/CVE-2026-45018","pt":"https://www.redsauce.net/pt/cves/CVE-2026-45018","de":"https://www.redsauce.net/de/cves/CVE-2026-45018","sk":"https://www.redsauce.net/sk/cves/CVE-2026-45018","el":"https://www.redsauce.net/el/cves/CVE-2026-45018"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-45018"}}