{"answers":{"affected":"2 open source packages ship an affected version, including h3.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86205 exists.","fix":"Upgrade h3 to 2.0.1-rc.18 or later.","what":"CVE-2026-86205 is a medium-severity vulnerability in h3js h3, published on 6 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-86205 and fix it if it is affected.\n\nWhat it is: CVE-2026-86205 is a medium-severity vulnerability in h3js h3, published on 6 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86205 exists.\n\nAffected packages and fixed versions:\n- h3 (npm): affected from 2.0.1-rc.17; fixed in 2.0.1-rc.18\n- h3 (npm): affected from 2.0.1-rc.17; fixed in 2.0.1-rc.18\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-2026-86205/ (Markdown: https://insights.sbomify.com/CVE-2026-86205/index.md)","id":"CVE-2026-86205","markdown":"https://insights.sbomify.com/CVE-2026-86205/index.md","name":"CVE-2026-86205","record":{"aliases":["GHSA-fp4x-ggrf-wmc6","GHSA-vhx4-2r84-67h4"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"h3 HTTP library","requires_auth":"none","summary":"Attackers can exploit unsanitized Referer headers in h3's redirectBack() to redirect users to external domains, bypassing origin validation.","user_interaction":"required","vuln_class":"open_redirect"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"VulnCheck","cpe":[],"cvss":{"score":5.3,"severity":"medium","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-601","name":"URL Redirection to Untrusted Site"}],"description":"h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack() utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a Location header interpreted by browsers as a protocol-relative redirect to an external domain.","ecosystems":["npm"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":false,"headline":"h3 before 2.0.1-rc.18 Open Redirect via redirectBack()","id":"CVE-2026-86205","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"npm","product":null,"products":[],"type":"open_redirect","year":"2026"},"n_packages":2,"n_references":2,"next":{"headline":"Access control filter bypass allows unauthorised access to APIs","id":"CVE-2026-86206"},"packages":[{"ecosystem":"npm","fixed":["2.0.1-rc.18"],"introduced":["2.0.1-rc.17"],"last_affected":[],"package":"h3","purl":null,"source":"GHSA-fp4x-ggrf-wmc6"},{"ecosystem":"npm","fixed":["2.0.1-rc.18"],"introduced":["2.0.1-rc.17"],"last_affected":[],"package":"h3","purl":"pkg:npm/h3","source":"GHSA-fp4x-ggrf-wmc6"}],"prev":{"headline":"PocketMine-MP before 5.39.2 Denial of Service via ModalFormResponsePacket","id":"CVE-2026-86204"},"products":["h3"],"published":"2026-09-06","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":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-08","vendors":["h3js"]},"summary":"Attackers can exploit unsanitized Referer headers in h3's redirectBack() to redirect users to external domains, bypassing origin validation.","url":"https://insights.sbomify.com/CVE-2026-86205/"}