CVE-2026-100724 (GCVE-0-2026-100724)
Vulnerability from cvelistv5
Published
2026-09-27 01:28
Modified
2026-10-29 21:15
Severity ?
6.3 (Medium) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
5.4 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
CWE
  • CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Summary
http4k (Maven package org.http4k:http4k-core) before 6.49.0.0, 5.42.0.0 and 4.51.0.0 uses substring (Contains) matching on the Host header by default in reverseProxy() and reverseProxyRouting() when dispatching to configured virtual hosts. If these functions are deployed as a public-facing inbound HTTP handler with two or more configured virtual hosts, a remote attacker can supply a Host header that merely contains a configured vhost name (for example Host: admin.evil.com for a vhost configured as "admin") and be routed to that vhost, bypassing routing-based authorization. The intended outbound-dispatch and test-time uses, where the Host value is set by the calling application, are not affected.
References
Impacted products
Vendor Product Version
http4k http4k Version: 6.0.0.0   < 6.49.0.0
Patch: 6.49.0.0
 Create a notification for this product.
   http4k http4k Version: 5.0.0.0   < 5.42.0.0
Patch: 5.42.0.0
 Create a notification for this product.
   http4k http4k Version: 0   < 4.51.0.0
Patch: 4.51.0.0
 Create a notification for this product.
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