{"id":"CVE-2026-25224","aliases":["GHSA-mrq3-vjjr-p77c"],"url":"https://o3.security/vulnerability/CVE-2026-25224","summary":"Fastify Vulnerable to DoS via Unbounded Memory Allocation in sendWebStream","details":"### Impact\nA Denial of Service vulnerability in Fastify’s Web Streams response handling can allow a remote client to exhaust server memory. Applications that return a `ReadableStream` (or `Response` with a Web Stream body) via `reply.send()` are impacted. A slow or non-reading client can trigger unbounded buffering when backpressure is ignored, leading to process crashes or severe degradation.\n\n### Patches\nThe issue is fixed in Fastify 5.7.3. Users should upgrade to 5.7.3 or later.\n\n### Workarounds\nAvoid sending Web Streams from Fastify responses (e.g., `ReadableStream` or `Response` bodies). Use Node.js streams (`stream.Readable`) or buffered payloads instead until the project can upgrade.\n\n### References\n- https://hackerone.com/reports/3524779","published":"2026-02-03T21:21:35.437Z","modified":"2026-08-12T03:51:25.844551899Z","cvss":{"score":3.7,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":{"score":0.00507,"percentile":0.41297,"asOf":"2026-09-02"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"fastify","fixedVersion":"5.7.3"}],"fix":{"url":"https://github.com/fastify/fastify/commit/eb11156396f6a5fedaceed0140aed2b7f026be37","label":"fastify/fastify@eb11156"},"references":[{"type":"WEB","url":"https://hackerone.com/reports/3524779"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25224.json"},{"type":"ADVISORY","url":"https://github.com/fastify/fastify/security/advisories/GHSA-mrq3-vjjr-p77c"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25224"},{"type":"FIX","url":"https://github.com/fastify/fastify/commit/eb11156396f6a5fedaceed0140aed2b7f026be37"},{"type":"PACKAGE","url":"https://github.com/fastify/fastify"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:25.844551899Z"}}