{"id":"CVE-2026-73494","title":"blaze is a Scala library for building asynchronous pipelines, with a focus on network IO","summary":"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…","severity":"high","cvss":7.4,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","cwe":["CWE-444"],"vendor":"http4s","product":"blaze","affected":["blaze < 0.23.18","blaze >= 1.0.0-M1, < 1.0.0-M42","blaze-http_2.13 < 0.23.18","blaze-http_2.13 >= 1.0.0-M1, < 1.0.0-M42","blaze-http_3 < 0.23.18","blaze-http_3 >= 1.0.0-M1, < 1.0.0-M42","http4s-blaze-server_2.13 < 0.23.18"],"published":"2026-09-14","updated":"2026-09-14","sourceUpdated":"2026-09-14T20:16:50.707","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-73494","references":[{"url":"https://github.com/http4s/blaze/commit/3f7c022e306631b006dcb43a1d7f65c0d1966f17","label":"security-advisories@github.com"},{"url":"https://github.com/http4s/blaze/commit/4eec2007806aa9acfefb00ebb636ddc39a147a96","label":"security-advisories@github.com"},{"url":"https://github.com/http4s/blaze/commit/927b67753a78c13c4445dac9307f511f5c4878c3","label":"security-advisories@github.com"},{"url":"https://github.com/http4s/blaze/commit/a54bc9cd31758335c7f24e29763622fd03fcf734","label":"security-advisories@github.com"},{"url":"https://github.com/http4s/blaze/commit/c47d9675f87603f11b32a11d503626bdf9be5c7a","label":"security-advisories@github.com"},{"url":"https://github.com/http4s/blaze/commit/e871ebb1d27f50c98fd56988526ce42d0fee74d6","label":"security-advisories@github.com"},{"url":"https://github.com/http4s/blaze/releases/tag/v0.23.18","label":"security-advisories@github.com"},{"url":"https://github.com/http4s/blaze/releases/tag/v1.0.0-M42","label":"security-advisories@github.com"},{"url":"https://github.com/http4s/blaze/security/advisories/GHSA-mhvj-jhpq-885v","label":"security-advisories@github.com"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-09-14T19:21:20.842876Z"},"ingestedAt":"2026-09-14T19:13:23.460Z","epss":0.00374,"epssPercentile":0.31334,"slug":"CVE-2026-73494","body":"## Overview\n\nblaze 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":40.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}