Answer in brief
CVE-2026-45018 records a Critical severity (CVSS 9.8) vulnerability in Chainlit: Command injection via MCP stdio transport allows unauthenticated remote code execution. The current sources do not mark it as known exploited. The current feed maps Chainlit/chainlit (generic), chainlit (pip), chainlit (pypi). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Chainlit/chainlit (generic), chainlit (pip), chainlit (pypi). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Chainlit/chainlitgeneric | >= 2.4.0rc0, < 2.12.0 | Not reported |
| chainlitpip | >=2.4.0rc0,<=2.11.1 | 2.12.0 |
| chainlitpypi | >=2.4.0rc0 <2.12.0 | 2.12.0 |
Published upstream
Aug 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 25, 2026
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.
Quoted source text, attributed separately from HOL analysis.