CVE-2026-120216
fastify is a web framework for Node.js
- Risk score
- 45/100
- CVSS
- 5.9 v3.1
- Published
- 2 Nov 2026
Open in the live forecast Today's forecast
What to know
- What it is
- fastify is a web framework for Node.js. In versions 5.8.0 through 5.12.7, when the server is configured with a nonzero handlerTimeout and a route returns a streaming response, a request whose stream has already sent its headers but stays open past the timeout crashes the server. When the timeout fires, Fastify tries t…
- Affected
- See advisory
- Fix
- Upgrade the product to 5.12.8 or later.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 5.9 medium
- On your watchlist: node.js
References
Original description
fastify is a web framework for Node.js. In versions 5.8.0 through 5.12.7, when the server is configured with a nonzero handlerTimeout and a route returns a streaming response, a request whose stream has already sent its headers but stays open past the timeout crashes the server. When the timeout fires, Fastify tries to send a new error response on a response that has already started, raising an uncaught ERR_HTTP_HEADERS_SENT that terminates the Node.js process and interrupts any other in-flight requests. An unauthenticated remote client can trigger this with a single request to an affected streaming endpoint, so the impact is availability only, and exploitation requires the non-default handlerTimeout to be set. The default handlerTimeout of 0 is not affected. The issue is fixed in fastify 5.12.8, and users should upgrade to 5.12.8 or later. As a workaround, set handlerTimeout to 0, which disables the affected timeout path.
Last activity 2 Nov 2026. Patch Forecast updates every hour.