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fastify

17 known vulnerabilities.

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  • Medium 5.9

    fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses

    fastify is a fast and low-overhead web framework for Node.js. In versions before 5.12.5, when a route registers a response trailer via reply.trailer() and is served over HTTP/2, fastify unconditionally sets the Transfer-Encoding: chunked header, which is forb…

  • Medium 6.1

    fastify vulnerable to X-Forwarded-* spoofing under trustProxy hop-count

    fastify is a fast and low overhead web framework for Node.js. Impact: the fix for CVE-2026-3635 added a guard on the forwarded-header reads used to derive the request host, protocol, hostname, ip, and ips values, checking the connecting address. That guard cl…

  • Medium 5.4
    CVE-2026-18504 Public exploit

    fastify vulnerable to schema validation bypass via root primitive coercion mismatch

    fastify is a fast and low overhead web framework for Node.js. Versions of fastify before 5.12.1 are affected by a schema validation bypass when a request body schema targets a root primitive value. When the schema validates a top-level primitive such as an in…

  • Medium 6.1

    Fastify request.protocol and request.host spoofable via X-Forwarded-Proto/Host from untrusted connections when trustProxy uses restrictive trust function

    Summary When trustProxy is configured with a restrictive trust function (e.g., a specific IP like trustProxy: '10.0.0.1', a subnet, a hop count, or a custom function), the request.protocol and request.host getters read X-Forwarded-Proto and X-Forwarded-Host h…

  • Medium 5.3

    Fastify's Missing End Anchor in "subtypeNameReg" Allows Malformed Content-Types to Pass Validation

    Fastify incorrectly accepts malformed `Content-Type` headers containing trailing characters after the subtype token, in violation of RFC 9110 §8.3.1(https://httpwg.org/specs/rfc9110.html#field.content-type). For example, a request sent with Content-Type: appl…

  • Medium 4.2

    Fastify vulnerable to Cross-Site Request Forgery (CSRF) attack via incorrect content type

    Fastify is a web framework with minimal overhead and plugin architecture. The attacker can use the incorrect `Content-Type` to bypass the `Pre-Flight` checking of `fetch`. `fetch()` requests with Content-Type’s essence as "application/x-www-form-urlencoded", …

  • Medium —

    Denial of service in fastify

    A denial of service vulnerability exists in Fastify v2.14.1 and v3.0.0-rc.4 that allows a malicious user to trigger resource exhaustion (when the allErrors option is used) with specially crafted schemas.