{"id":"CVE-2026-120216","aliases":["CLSA-2026-1793791632","CLSA-2026-1793801979","EUVD-2026-115128","GHSA-3qgw-9275-xf8w"],"status":"published","title":"fastify vulnerable to Denial of Service via uncaught exception on handlerTimeout with streaming responses","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.","severity":{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00329,"percentile":0.26362,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-248"],"published":"2026-11-02T11:08:00Z","modified":"2026-11-04T19:00:36Z","fixes":[{"ecosystem":"TuxCare:npm","package":"fastify","fixed_in":["5.12.4-tuxcare.2"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"TuxCare:npm","package":"fastify","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.12.5-tuxcare.0"},{"fixed":"5.12.5-tuxcare.1"}]}],"versions":["5.12.5"],"bundled":2},{"source":"osv","ecosystem":"TuxCare:npm","package":"fastify","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.12.4-tuxcare.0"},{"fixed":"5.12.4-tuxcare.2"}]}],"versions":["5.12.4","5.12.4-tuxcare.1"]}],"products":[{"vendor":"@clerk","product":"fastify"},{"vendor":"fastify","product":"fastify"}],"references":[{"url":"https://github.com/fastify/fastify/security/advisories/GHSA-3qgw-9275-xf8w","tags":["advisory"]},{"url":"https://cna.openjsf.org/security-advisories.html","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/120xxx/CVE-2026-120216.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120216","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-120216","title":"fastify vulnerable to Denial of Service via uncaught exception on handlerTimeout with streaming responses","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.","status":"published","published":"2026-11-02T11:08:00.038Z","modified":"2026-11-02T16:56:16.784Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-248"],"updated_at":"2026-11-02T18:00:08.034842Z"}],"euvd":[{"id":"EUVD-2026-115128","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.","status":"published","published":"2026-11-02T11:08:00Z","modified":"2026-11-02T16:56:16Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T05:08:40.251173Z"}],"nvd":[{"id":"CVE-2026-120216","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.","status":"published","published":"2026-11-02T11:17:31.553Z","modified":"2026-11-02T17:17:39.87Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-248"],"updated_at":"2026-11-02T20:51:44.219211Z"}],"osv":[{"id":"CVE-2026-120216","title":"fastify vulnerable to Denial of Service via uncaught exception on handlerTimeout with streaming responses","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.","status":"published","published":"2026-11-02T11:08:00.038Z","modified":"2026-11-09T10:45:34.317385692Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-248"],"updated_at":"2026-11-09T10:53:57.550641Z"},{"id":"CLSA-2026-1793791632","title":"TuxCare security update for fastify (2 CVEs)","description":"TuxCare rebuilt fastify to address 2 CVEs. Fixed in 5.12.5-tuxcare.1.","status":"published","published":"2026-11-04T12:27:13Z","modified":"2026-11-04T14:45:06.150121554Z","updated_at":"2026-11-04T15:03:54.132276Z"},{"id":"CLSA-2026-1793801979","title":"TuxCare security update for fastify (1 CVE)","description":"TuxCare rebuilt fastify to address 1 CVE. Fixed in 5.12.4-tuxcare.2.","status":"published","published":"2026-11-04T15:19:40Z","modified":"2026-11-04T19:00:36.311260548Z","updated_at":"2026-11-04T19:15:03.6858Z"}]}}