Answer in brief
CVE-2026-73494 records a High severity (CVSS 7.4) vulnerability in blaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser. The current sources do not mark it as known exploited. The current feed maps http4s/blaze (generic), org.http4s/blaze-http_2.13 (generic), org.http4s/blaze-http_3 (generic), org.http4s/http4s-blaze-server_2.13 (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps http4s/blaze (generic), org.http4s/blaze-http_2.13 (generic), org.http4s/blaze-http_3 (generic), org.http4s/http4s-blaze-server_2.13 (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| http4s/blazegeneric | < 0.23.18 || >= 1.0.0-M1, < 1.0.0-M42 | Not reported |
| org.http4s/blaze-http_2.13generic | < 0.23.18 || >= 1.0.0-M1, < 1.0.0-M42 | Not reported |
| org.http4s/blaze-http_3generic | < 0.23.18 || >= 1.0.0-M1, < 1.0.0-M42 | Not reported |
| org.http4s/http4s-blaze-server_2.13generic | < 0.23.18 | Not reported |
| org.http4s:blaze-http_2.13maven | >=0 <0.23.18 | 0.23.18 |
| org.http4s:blaze-http_2.13maven | >=1.0.0-M1 <1.0.0-M42 | 1.0.0-M42 |
| org.http4s:blaze-http_2.13maven | <=0.23.17 | 0.23.18 |
| org.http4s:blaze-http_2.13maven | >=1.0.0-M1,<=1.0.0-M41 | 1.0.0-M42 |
| org.http4s:blaze-http_3maven | >=0 <0.23.18 | 0.23.18 |
| org.http4s:blaze-http_3maven | >=1.0.0-M1 <1.0.0-M42 | 1.0.0-M42 |
| org.http4s:blaze-http_3maven | <=0.23.17 | 0.23.18 |
| org.http4s:blaze-http_3maven | >=1.0.0-M1,<=1.0.0-M41 | 1.0.0-M42 |
| org.http4s:http4s-blaze-server_2.13maven | >=0 <0.23.18 | 0.23.18 |
| org.http4s:http4s-blaze-server_2.13maven | <=0.23.17 | 0.23.18 |
Published upstream
Sep 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 8, 2026
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.
Quoted source text, attributed separately from HOL analysis.