cve.bz

CVE-2026-73494

7.4 highEPSS 0.6%

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.

CVSS 3.1
7.4CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS
0.6% chance of exploitation in the next 30 days; higher than 49% of CVEs (scores of 2026-10-25)
CWE
CWE-444
Published
Modified
Record from
the NVD, synced

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-mhvj-jhpq-885vMavenorg.http4s:http4s-blaze-server_2.13<0.23.180.23.18
GHSA-mhvj-jhpq-885vMavenorg.http4s:blaze-http_2.13<0.23.180.23.18
GHSA-mhvj-jhpq-885vMavenorg.http4s:blaze-http_3<0.23.180.23.18
GHSA-mhvj-jhpq-885vMavenorg.http4s:blaze-http_3>=1.0.0-M1 <1.0.0-M421.0.0-M42
GHSA-mhvj-jhpq-885vMavenorg.http4s:blaze-http_2.13>=1.0.0-M1 <1.0.0-M421.0.0-M42

References

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