Server-side Request Forgery (SSRF) Affecting chainlit package, versions [2.4.0rc0,2.12.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-CHAINLIT-19268245
- published26 Aug 2026
- disclosed25 Aug 2026
- creditqvipin, ladderlogix
Introduced: 25 Aug 2026
NewCVE-2026-45019 (opens in a new tab)How to fix?
Upgrade chainlit to version 2.12.0 or higher.
Overview
chainlit is a Build Conversational AI.
Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) via the /mcp connect handling in backend/chainlit/server.py. An attacker can force the server to make outbound HTTP requests to arbitrary internal or external URLs by sending a POST /mcp request for the sse or streamable-http transport with a user-controlled url and headers. This lets an unauthenticated client probe internal services and cloud metadata endpoints, and send forged requests with attacker-chosen headers such as Authorization and Cookie, breaking the security of deployments with MCP enabled.
Workarounds
- Set
features.mcp.enabled = falsein.chainlit/config.tomlto disable/mcpentirely and block the SSRF attack path. - Restrict outbound egress from the Chainlit host, for example with firewall rules that block access to internal address ranges and cloud metadata endpoints, to prevent the server from reaching attacker-chosen destinations.
- Configure authentication by registering an auth callback so
/mcprequires an authenticated session, which removes the unauthenticated attack path.