GHSA-MHVJ-JHPQ-885V

blaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser

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.

Workarounds

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.

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.

GHSA-MHVJ-JHPQ-885V has a CVSS score of 7.4 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.23.18, 1.0.0-M42); upgrading removes the vulnerable code path.

Kodem intelligence

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1. What is GHSA-MHVJ-JHPQ-885V? GHSA-MHVJ-JHPQ-885V is a high-severity security vulnerability in org.http4s:http4s-blaze-server_2.13 (maven), affecting versions <= 0.23.17. It is fixed in 0.23.18, 1.0.0-M42.
2. How severe is GHSA-MHVJ-JHPQ-885V? GHSA-MHVJ-JHPQ-885V has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by GHSA-MHVJ-JHPQ-885V?
   • org.http4s:http4s-blaze-server_2.13 (maven) (versions <= 0.23.17)
   • org.http4s:blaze-http_2.13 (maven) (versions <= 0.23.17)
   • org.http4s:blaze-http_3 (maven) (versions <= 0.23.17)
4. Is there a fix for GHSA-MHVJ-JHPQ-885V? Yes. GHSA-MHVJ-JHPQ-885V is fixed in 0.23.18, 1.0.0-M42. Upgrade to this version or later.
5. Is GHSA-MHVJ-JHPQ-885V exploitable, and should I be worried? Whether GHSA-MHVJ-JHPQ-885V is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-MHVJ-JHPQ-885V is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-MHVJ-JHPQ-885V?
   • Upgrade org.http4s:http4s-blaze-server_2.13 to 0.23.18 or later
   • Upgrade org.http4s:blaze-http_2.13 to 0.23.18 or later
   • Upgrade org.http4s:blaze-http_3 to 0.23.18 or later
   • Upgrade org.http4s:blaze-http_3 to 1.0.0-M42 or later
   • Upgrade org.http4s:blaze-http_2.13 to 1.0.0-M42 or later

Other vulnerabilities in org.http4s:http4s-blaze-server_2.13