{"id":"CVE-2026-28898","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-28898","summary":"SwiftNIO HTTP/2: HTTP/2-to-HTTP/1 Request Smuggling via unvalidated :path pseudo-header in HTTP2ToHTTP1Codec","details":"swift-nio-http2's HTTP/2-to-HTTP/1.1 codec (`HTTP2FramePayloadToHTTP1ServerCodec` / `HTTP2ToHTTP1ServerCodec`) did not validate pseudo-header values for control characters before placing them into the translated HTTP/1.1 message. A remote attacker could send an HTTP/2 request containing CR (\\r), LF (\\n), or NUL (\\0) bytes in pseudo-header values such as `:path`, and when the server translated this to HTTP/1.1 — for example in a reverse-proxy configuration — the resulting output could contain injected headers or entirely smuggled requests.\n\nThis is an HTTP/2-to-HTTP/1.1 request smuggling vulnerability. HTTP/2's binary framing means that CRLF bytes are never parsed as line terminators at the HTTP/2 layer, so they pass through transparently to the HTTP/1.1 output. Any swift-nio-http2 server that translates HTTP/2 requests to HTTP/1.1 and forwards them to a backend is affected. Server-side Swift frameworks such as Vapor that use this codec in a reverse-proxy pattern are directly affected.\n\nThis vulnerability is related to https://github.com/advisories/GHSA-7fj7-39wj-c64f in swift-nio, which addressed CRLF injection in HTTP/1.1 header values but did not cover pseudo-header values in the HTTP/2 layer.\n\nThis vulnerability is also related to https://github.com/advisories/GHSA-cq87-8r7h-962v in swift-nio, which addressed CRLF injection in HTTP/1.1 version, method and path.\n\nswift-nio-http2 1.44.0 adds validation of all pseudo-header values (:path, :authority, :scheme, :method, and :status) at both the HPACK header validation layer and the HTTP/2-to-HTTP/1.1 translation layer. Requests or responses containing CR, LF, or NUL bytes in any pseudo-header value are now rejected with a connection error.\n\nSwiftNIO recommends all adopters upgrade to 1.44.0 as soon as possible.\n\nSwiftNIO thanks @kuranikaran for filing this issue and the support in fixing it.","published":"2026-06-12T15:08:16Z","modified":"2026-07-29T05:15:34.230069609Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"},"epss":{"score":0.0031,"percentile":0.23358,"asOf":"2026-09-01"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"SwiftURL","name":"github.com/apple/swift-nio-http2","fixedVersion":"1.44.0"}],"fix":{"url":"https://github.com/apple/swift-nio-http2/commit/61d1b44f6e4e118792be1cff88ee2bc0267c6f9a","label":"apple/swift-nio-http2@61d1b44"},"references":[{"type":"WEB","url":"https://github.com/apple/swift-nio-http2/security/advisories/GHSA-4px2-pw77-vc85"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-28898"},{"type":"WEB","url":"https://github.com/apple/swift-nio-http2/commit/61d1b44f6e4e118792be1cff88ee2bc0267c6f9a"},{"type":"PACKAGE","url":"https://github.com/apple/swift-nio-http2"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-29T05:15:34.230069609Z"}}