{"answers":{"affected":"6 open source packages ship an affected version, including org.http4k:http4k-core.","exploited":"There is no known exploitation of CVE-2026-100724 in the wild and no public exploit code.","fix":"Upgrade org.http4k:http4k-core to a fixed version for your release line: 4.51.0.0, 5.42.0.0 or 6.49.0.0.","what":"CVE-2026-100724 is a medium-severity authentication bypass vulnerability in http4k, published on 27 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-100724 and fix it if it is affected.\n\nWhat it is: CVE-2026-100724 is a medium-severity authentication bypass vulnerability in http4k, published on 27 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-100724 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- org.http4k:http4k-core (Maven): affected all versions; fixed in 4.51.0.0\n- org.http4k:http4k-core (Maven): affected all versions; fixed in 4.51.0.0\n- org.http4k:http4k-core (Maven): affected from 5.0.0.0; fixed in 5.42.0.0\n- org.http4k:http4k-core (Maven): affected from 5.0.0.0; fixed in 5.42.0.0\n- org.http4k:http4k-core (Maven): affected from 6.0.0.0; fixed in 6.49.0.0\n- org.http4k:http4k-core (Maven): affected from 6.0.0.0; fixed in 6.49.0.0\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-100724/ (Markdown: https://insights.sbomify.com/CVE-2026-100724/index.md)","id":"CVE-2026-100724","markdown":"https://insights.sbomify.com/CVE-2026-100724/index.md","name":"CVE-2026-100724","record":{"aliases":["GHSA-9hc9-gcfq-xg98","GHSA-jrpc-7vxp-69p6"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":true,"product_category":"Kotlin HTTP library","requires_auth":"none","summary":"Attackers can bypass routing-based authorization in http4k reverse proxies by spoofing the Host header to match configured virtual hosts.","user_interaction":"not_required","vuln_class":"auth_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"VulnCheck","cpe":[],"cvss":{"score":6.3,"severity":"medium","source":"cna","vector":"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","version":"4.0"},"cwes":[{"id":"CWE-444","name":"Inconsistent Interpretation of HTTP Requests"}],"description":"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.","ecosystems":["Maven"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":false,"headline":"http4k before 6.49.0.0 Host Header Routing Bypass via reverseProxy","id":"CVE-2026-100724","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Maven","product":null,"products":[],"type":"auth_bypass","year":"2026"},"n_packages":6,"n_references":4,"next":{"headline":"http4k before 6.48.0.0 Cookie Scoping Bypass via BasicCookieStorage","id":"CVE-2026-100725"},"packages":[{"ecosystem":"Maven","fixed":["4.51.0.0"],"introduced":["0"],"last_affected":[],"package":"org.http4k:http4k-core","purl":null,"source":"GHSA-jrpc-7vxp-69p6"},{"ecosystem":"Maven","fixed":["4.51.0.0"],"introduced":["0"],"last_affected":[],"package":"org.http4k:http4k-core","purl":"pkg:maven/org.http4k/http4k-core","source":"GHSA-jrpc-7vxp-69p6"},{"ecosystem":"Maven","fixed":["5.42.0.0"],"introduced":["5.0.0.0"],"last_affected":[],"package":"org.http4k:http4k-core","purl":null,"source":"GHSA-jrpc-7vxp-69p6"},{"ecosystem":"Maven","fixed":["5.42.0.0"],"introduced":["5.0.0.0"],"last_affected":[],"package":"org.http4k:http4k-core","purl":"pkg:maven/org.http4k/http4k-core","source":"GHSA-jrpc-7vxp-69p6"},{"ecosystem":"Maven","fixed":["6.49.0.0"],"introduced":["6.0.0.0"],"last_affected":[],"package":"org.http4k:http4k-core","purl":null,"source":"GHSA-jrpc-7vxp-69p6"},{"ecosystem":"Maven","fixed":["6.49.0.0"],"introduced":["6.0.0.0"],"last_affected":[],"package":"org.http4k:http4k-core","purl":"pkg:maven/org.http4k/http4k-core","source":"GHSA-jrpc-7vxp-69p6"}],"prev":{"headline":"vm2 before 3.12.2 Memory Disclosure via zlib Buffer Pool","id":"CVE-2026-100723"},"products":["http4k"],"published":"2026-09-27","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-10-29","vendors":["http4k"]},"summary":"Attackers can bypass routing-based authorization in http4k reverse proxies by spoofing the Host header to match configured virtual hosts.","url":"https://insights.sbomify.com/CVE-2026-100724/"}