GHSA-mhvj-jhpq-885vHigh· 7.4▾ Twilightblaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 40.7 · likelihood 0 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Five independent HTTP/1.1 conformance laxities in blaze's hand-written Java parser (http/src/main/java/org/http4s/blaze/http/parser/) cause request-boundary disagreement with a stricter intermediary. All are reachable from a default BlazeServerBuilder with no non-default configuration.
Actual exploitability depends on the fronting proxy — a boundary disagreement requires a pair of parsers that disagree. Where the proxy forwards the malformed bytes and derives a different message boundary, the consequences are the standard set: front-end ACL/auth bypass, response-queue poisoning on pooled backend connections, and cache poisoning. Risk concentrates on lenient or legacy intermediaries.
Deploy behind an RFC-strict reverse proxy (nginx, HAProxy, Envoy, ALB) that rejects or re-serializes malformed requests at the edge; this neutralizes most of these for deployments that cannot upgrade immediately.
org.http4s:http4s-blaze-server_2.13 <= 0.23.17org.http4s:blaze-http_2.13 <= 0.23.17org.http4s:blaze-http_3 <= 0.23.17org.http4s:blaze-http_3 >= 1.0.0-M1, <= 1.0.0-M41org.http4s:blaze-http_2.13 >= 1.0.0-M1, <= 1.0.0-M41Upgrade to a patched release:
org.http4s:http4s-blaze-server_2.13 0.23.18org.http4s:blaze-http_2.13 0.23.18org.http4s:blaze-http_3 0.23.18org.http4s:blaze-http_3 1.0.0-M42org.http4s:blaze-http_2.13 1.0.0-M42Connected by shared product, vendor, weakness, or advisory.
CVE-2026-73494High· 7.4blaze is a Scala library for building asynchronous pipelines, with a focus on network IO
GHSA-46q4-43ph-c6frHigh· 7.4blaze: Chunked-body trailer fields promoted into Request.headers in blaze-server (front-end header-sanitization bypass)
GHSA-7ppr-r889-mcf2High· 7.5blaze: Unbounded WebSocket message aggregation in http4s-blaze-server
CVE-2026-73495High· 7.4blaze is a Scala library for building asynchronous pipelines, with a focus on network IO
CVE-2026-69205High· 8.7Http4s is a Scala interface for HTTP services
CVE-2026-69216Medium· 5.4Http4s is a Scala interface for HTTP services