{"cve":"CVE-2026-33805","nvd":{"published":"2026-04-15T11:16:34.990","modified":"2026-10-26T22:10:00.163","status":"Modified","description":"@fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This allows attackers to retroactively strip proxy-added headers from upstream requests by listing them in the Connection header value. Any header added by the proxy for routing, access control, or security purposes can be selectively removed by a client. @fastify/http-proxy is also affected as it delegates to @fastify/reply-from. \n\nUpgrade to @fastify/reply-from v12.6.2 or @fastify/http-proxy v11.4.4 or later.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:H/SA:N","score":9.0},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N","score":8.6},"cwes":["CWE-644","CWE-444"],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-gwhp-pf74-vj37","https://access.redhat.com/errata/RHSA-2026:10175","https://access.redhat.com/security/cve/CVE-2026-33805","https://bugzilla.redhat.com/show_bug.cgi?id=2458651"],"products":["fastify:fastify\\/http-proxy","fastify:reply-from"],"source":"nvd","synced_at":"2026-10-26T22:26:44.656832877+00:00"},"epss":{"cve":"CVE-2026-33805","score":0.00441,"percentile":0.38047,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-gwhp-pf74-vj37","url":"https://osv.dev/vulnerability/GHSA-gwhp-pf74-vj37","summary":"Fastify's connection header abuse enables stripping of proxy-added headers","modified":"2026-09-10T03:51:01.795868641Z","packages":[{"ecosystem":"npm","name":"@fastify/reply-from","purl":"pkg:npm/%40fastify/reply-from","ranges":["<12.6.2"],"fixed":["12.6.2"]},{"ecosystem":"npm","name":"@fastify/http-proxy","purl":"pkg:npm/%40fastify/http-proxy","ranges":["<11.4.4"],"fixed":["11.4.4"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}