{"id":"CVE-2026-73494","aliases":["GHSA-mhvj-jhpq-885v"],"url":"https://o3.security/vulnerability/CVE-2026-73494","summary":"blaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser","details":"blaze is a Scala library for building asynchronous pipelines, with a focus on network IO. Prior to 0.23.18 and from 1.0.0-M1 until 1.0.0-M42, five HTTP/1.1 conformance laxities in the hand-written Java parser under http/src/main/java/org/http4s/blaze/http/parser/ can cause blaze to derive a different request boundary than a stricter fronting intermediary. A default BlazeServerBuilder accepts invalid or valueless header field names that violate tchar syntax, obsolete folded field lines (obs-fold), unsupported Transfer-Encoding values, duplicate Content-Length fields, and requests containing both Transfer-Encoding and Content-Length. If a lenient or legacy proxy forwards the malformed bytes but interprets them differently, the disagreement can permit front-end authorization bypass, response-queue poisoning on pooled backend connections, or cache poisoning. Exploitation requires a pair of disagreeing parsers; no non-default blaze configuration is required. The affected checks are enforced in BodyAndHeaderParser and Http1ServerParser. This issue is fixed in versions 0.23.18 and 1.0.0-M42.","published":"2026-09-14T17:33:49.671Z","modified":"2026-09-16T08:05:21.112096Z","cvss":{"score":7.4,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"},"epss":{"score":0.00374,"percentile":0.30937,"asOf":"2026-09-15"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"org.http4s:http4s-blaze-server_2.13","fixedVersion":"0.23.18"},{"ecosystem":"Maven","name":"org.http4s:blaze-http_2.13","fixedVersion":"0.23.18"},{"ecosystem":"Maven","name":"org.http4s:blaze-http_3","fixedVersion":"0.23.18"},{"ecosystem":"Maven","name":"org.http4s:blaze-http_3","fixedVersion":"1.0.0-M42"},{"ecosystem":"Maven","name":"org.http4s:blaze-http_2.13","fixedVersion":"1.0.0-M42"}],"fix":{"url":"https://github.com/http4s/blaze/commit/3f7c022e306631b006dcb43a1d7f65c0d1966f17","label":"http4s/blaze@3f7c022"},"references":[{"type":"WEB","url":"https://github.com/http4s/blaze/releases/tag/v0.23.18"},{"type":"WEB","url":"https://github.com/http4s/blaze/releases/tag/v1.0.0-M42"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73494.json"},{"type":"ADVISORY","url":"https://github.com/http4s/blaze/security/advisories/GHSA-mhvj-jhpq-885v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73494"},{"type":"FIX","url":"https://github.com/http4s/blaze/commit/3f7c022e306631b006dcb43a1d7f65c0d1966f17"},{"type":"FIX","url":"https://github.com/http4s/blaze/commit/4eec2007806aa9acfefb00ebb636ddc39a147a96"},{"type":"FIX","url":"https://github.com/http4s/blaze/commit/927b67753a78c13c4445dac9307f511f5c4878c3"},{"type":"FIX","url":"https://github.com/http4s/blaze/commit/a54bc9cd31758335c7f24e29763622fd03fcf734"},{"type":"FIX","url":"https://github.com/http4s/blaze/commit/c47d9675f87603f11b32a11d503626bdf9be5c7a"},{"type":"FIX","url":"https://github.com/http4s/blaze/commit/e871ebb1d27f50c98fd56988526ce42d0fee74d6"},{"type":"PACKAGE","url":"https://github.com/http4s/blaze"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-16T08:05:21.112096Z"}}