{"affected":[{"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-q3g2-m552-3r9c/GHSA-q3g2-m552-3r9c.json"},"package":{"ecosystem":"SwiftURL","name":"swift-nio-http2","purl":"pkg:swift/swift-nio-http2"},"ranges":[{"events":[{"introduced":"0"},{"fixed":"1.45.0"}],"type":"SEMVER"}]}],"aliases":["CVE-2026-64785"],"database_specific":{"cwe_ids":["CWE-113","CWE-444"],"github_reviewed":true,"github_reviewed_at":"2026-07-24T21:52:10Z","nvd_published_at":"2026-07-23T20:17:21Z","severity":"MODERATE"},"details":"## Summary\n\nSwiftNIO HTTP/2 was missing validation on inbound HEADERS frames that let\nCR, LF, NUL, SP and other control characters reach an HTTP/1.1 backend\nthrough NIOHTTP2's HTTP/2-to-HTTP/1 codec, enabling HTTP request smuggling\nor response splitting.\n\n## Impact\n\nTwo related gaps in inbound header validation, against any application\nusing HTTP2ToHTTP1Codec (or HTTP2FramePayloadToHTTP1Codec) to front an\nHTTP/1.1 backend:\n\nRegular header field values were only checked against a forbidden-name\nlist (connection, transfer-encoding, proxy-connection, keep-alive,\nupgrade); the value itself was never inspected. An attacker-controlled\nregular header field value containing CR or LF passed validation and, once\nserialized as `name: value CRLF` by the codec, terminated the field early\nand injected extra header lines into the outbound HTTP/1.1 message.\n\nPseudo-header values (`:path` in particular) were only checked against\nCR, LF and NUL. A `:path` value containing SP serializes into the\nrequest-target of `METHOD SP request-target SP HTTP-version CRLF`, so a\nvalue like `/a HTTP/1.1` produces `GET /a HTTP/1.1 HTTP/1.1` — a\nparser-differential request line depending on whether a downstream reader\ntakes the first or last SP-delimited token as the version.\n\nNeither of these is reachable on a stock pipeline: NIOHTTP1's outbound\nvalidator (`enableOutboundHeaderValidation`, on by default) already rejects\nthese characters on write. The exposure is pipelines that skip outbound\nvalidation, or any code that reads validated-looking `HTTPRequestHead.headers`\nand forwards the values on trusting that HTTP/2 already checked them.\n\n## Fix\n\nFixed in 48bfd90 and 45bdf67.\n\n## Mitigation\n\nUpgrade to 1.45.0","id":"GHSA-q3g2-m552-3r9c","modified":"2026-07-24T22:11:43.421919Z","published":"2026-07-24T21:52:10Z","references":[{"type":"WEB","url":"https://github.com/apple/swift-nio-http2/security/advisories/GHSA-q3g2-m552-3r9c"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64785"},{"type":"WEB","url":"https://github.com/apple/swift-nio-http2/commit/45bdf670248be5f16ec0340e125dca285536f0fb"},{"type":"WEB","url":"https://github.com/apple/swift-nio-http2/commit/48bfd9067d7d1d15c4789440127a0cf36222ea43"},{"type":"PACKAGE","url":"https://github.com/apple/swift-nio-http2"},{"type":"WEB","url":"https://github.com/apple/swift-nio-http2/releases/tag/1.45.0"}],"schema_version":"1.9.0","severity":[{"score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","type":"CVSS_V3"},{"score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","type":"CVSS_V4"}],"summary":"swift-nio-http2: Missing CR/LF/NUL validation in header values"}