CVE-2026-73494
blaze is a Scala library for building asynchronous pipelines, with a focus on network IO.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| maven | org.http4s:http4s-blaze-server_2.13 | <= 0.23.17 | 0.23.18 |
| maven | org.http4s:blaze-http_2.13 | <= 0.23.17 | 0.23.18 |
| maven | org.http4s:blaze-http_3 | <= 0.23.17 | 0.23.18 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-mhvj-jhpq-885v
- https://github.com/http4s/blaze/security/advisories/GHSA-mhvj-jhpq-885v
- https://github.com/http4s/blaze/commit/3f7c022e306631b006dcb43a1d7f65c0d1966f17
- https://github.com/http4s/blaze/commit/4eec2007806aa9acfefb00ebb636ddc39a147a96
- https://github.com/http4s/blaze/commit/927b67753a78c13c4445dac9307f511f5c4878c3
- https://github.com/http4s/blaze/commit/a54bc9cd31758335c7f24e29763622fd03fcf734
- https://github.com/http4s/blaze/commit/c47d9675f87603f11b32a11d503626bdf9be5c7a
- https://github.com/http4s/blaze/commit/e871ebb1d27f50c98fd56988526ce42d0fee74d6
- https://github.com/http4s/blaze/releases/tag/v0.23.18
- https://github.com/http4s/blaze/releases/tag/v1.0.0-M42