GHSA-mhvj-jhpq-885v is a high-severity (CVSS 7.4) CWE-444 vulnerability in org.http4s:http4s-blaze-server_2.13. A fix is available for org.http4s:http4s-blaze-server_2.13 — see the affected versions and patch details below.
blaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-mhvj-jhpq-885v.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-mhvj-jhpq-885v by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 380,066 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
org.http4s:http4s-blaze-server_2.13☕org.http4s:blaze-http_2.13☕org.http4s:blaze-http_3☕org.http4s:blaze-http_3☕org.http4s:blaze-http_2.13Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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 | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.http4s:http4s-blaze-server_2.13 | all versions | 0.23.18org.http4s:http4s-blaze-server_2.13:0.23.18 |
| ☕Maven | org.http4s:blaze-http_2.13 | all versions | 0.23.18org.http4s:blaze-http_2.13:0.23.18 |
| ☕Maven | org.http4s:blaze-http_3 | all versions | 0.23.18org.http4s:blaze-http_3:0.23.18 |
| ☕Maven | org.http4s:blaze-http_3 | ≥ 1.0.0-M1&&< 1.0.0-M42 | 1.0.0-M42org.http4s:blaze-http_3:1.0.0-M42 |
| ☕Maven | org.http4s:blaze-http_2.13 | ≥ 1.0.0-M1&&< 1.0.0-M42 | 1.0.0-M42org.http4s:blaze-http_2.13:1.0.0-M42 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4s:http4s-blaze-server_2.13, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.http4s:http4s-blaze-server_2.13 to 0.23.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mhvj-jhpq-885v is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is GHSA-mhvj-jhpq-885v in your dependencies?
Find it across Maven, including transitive dependencies.