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CVE-2026-73494— blaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser

Quick assessment

Affected
http4s blaze
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

原文： > 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/htt

CVSS 7.4 · High

Affected Version Matrix 7

VendorProduct Version RangeStatus
http4s blaze < 0.23.18 affected
>= 1.0.0-M1, < 1.0.0-M42 affected
org.http4s blaze-http_2.13 < 0.23.18 affected
>= 1.0.0-M1, < 1.0.0-M42 affected
org.http4s blaze-http_3 < 0.23.18 affected
>= 1.0.0-M1, < 1.0.0-M42 affected
org.http4s http4s-blaze-server_2.13 < 0.23.18 affected
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I. Basic Information for CVE-2026-73494

Vulnerability Information
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Vulnerability Title
blaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
HTTP请求的解释不一致性(HTTP请求私运)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
http4s blaze < 0.23.18 -
org.http4s blaze-http_2.13 < 0.23.18 -
org.http4s blaze-http_3 < 0.23.18 -
org.http4s http4s-blaze-server_2.13 < 0.23.18 -

II. Public POCs for CVE-2026-73494

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III. Intelligence Information for CVE-2026-73494

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Patches & Fixes for CVE-2026-73494 (6)

Vendor Advisories for CVE-2026-73494 (1)

Vendor Pages for CVE-2026-73494 (2)

IV. Related Vulnerabilities

Same product: blaze
Same vendor: http4s
Same weakness: CWE-444

V. Comments for CVE-2026-73494

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