{"action":"Upgrade fastify to 5.12.2 or later.","affected":[{"fixed":"5.12.2","introduced":"0"}],"component":"fastify","cve_ids":["CVE-2026-84504"],"ecosystem":"npm","epss":0.00428,"exploited":false,"fixed_versions":["5.12.2"],"ghsa_id":"GHSA-667r-xxjv-c9mm","id":"tcs_01M5KF5XZJTY2YG8MNVRSAVQDH","modified_at":"2026-10-01T00:00:04.671540564Z","published_at":"2026-09-30T23:45:45Z","references":["https://osv.dev/vulnerability/GHSA-667r-xxjv-c9mm","https://github.com/fastify/fastify/security/advisories/GHSA-667r-xxjv-c9mm","https://nvd.nist.gov/vuln/detail/CVE-2026-84504","https://github.com/fastify/fastify/commit/f02d8d4ab1ab208f10819c4dc213595b06497833","https://cna.openjsf.org/security-advisories.html","https://github.com/fastify/fastify","https://github.com/fastify/fastify/releases/tag/v5.12.2"],"severity":{"label":"high","score":8.1},"sources":[{"source":"osv","source_id":"GHSA-667r-xxjv-c9mm","url":"https://osv.dev/vulnerability/GHSA-667r-xxjv-c9mm"}],"summary":"fastify vulnerable to request body replacement via an async validation result collision"}