{"id":"CVE-2021-21322","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-21322","generatedAt":"2026-10-27T21:19:05.062Z","title":"fastify-http-proxy is an npm package which is a fastify plugin for proxying your http requests to another server, with hooks.","description":"fastify-http-proxy is an npm package which is a fastify plugin for proxying your http requests to another server, with hooks. By crafting a specific URL, it is possible to escape the prefix of the proxied backend service. If the base url of the proxied server is `/pub/`, a user expect that accessing `/priv` on the target service would not be possible. In affected versions, it is possible. This is fixed in version 4.3.1.","published":"2021-03-02T04:15:13.000Z","lastModified":"2026-06-17T03:35:18.000Z","status":"Modified","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-20"],"affected":["fastify-http-proxy project/fastify-http-proxy"],"epss":{"score":0.01627,"percentile":0.75994,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (1.63%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://github.com/fastify/fastify-http-proxy/commit/02d9b43c770aa16bc44470edecfaeb7c17985016","tags":["Patch","Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-c4qr-gmr9-v23w","tags":["Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://www.npmjs.com/package/fastify-http-proxy","tags":["Product","Third Party Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/fastify/fastify-http-proxy/commit/02d9b43c770aa16bc44470edecfaeb7c17985016","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/fastify/fastify-http-proxy/security/advisories/GHSA-c4qr-gmr9-v23w","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.npmjs.com/package/fastify-http-proxy","tags":["Product","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-21322","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}