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Fencer Intel
high 7.4

CVE-2026-73494 json

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

published 3mo ago modified last mo. also EUVD-2026-77697 , GHSA-mhvj-jhpq-885v

cvss
7.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.http4s:http4s-blaze-server_2.13 0.23.18
  • maven org.http4s:blaze-http_2.13 0.23.18, 1.0.0-M42
  • maven org.http4s:blaze-http_3 0.23.18, 1.0.0-M42
  • typelevel blaze 0.23.18, 1.0.0-m42
  • org.http4s blaze-http_2.13 0.23.18, 1.0.0-m42
  • org.http4s blaze-http_3 0.23.18, 1.0.0-m42
  • org.http4s http4s-blaze-server_2.13 0.23.18

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
last mo.

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
GitHub 3.1 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
maven org.http4s:http4s-blaze-server_2.13
<0.23.18
0.23.18
maven org.http4s:blaze-http_2.13
<0.23.18
>=1.0.0-M1, <1.0.0-M42
0.23.18
1.0.0-M42
maven org.http4s:blaze-http_3
<0.23.18
>=1.0.0-M1, <1.0.0-M42
0.23.18
1.0.0-M42

Affected products

  • http4s blaze
  • org.http4s blaze-http_2.13
  • org.http4s blaze-http_3
  • org.http4s http4s-blaze-server_2.13

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.