{"answers":{"affected":"2 open source packages ship an affected version, including fastify. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-84428 in the wild and no public exploit code.","fix":"Upgrade fastify to 5.12.2 or later.","what":"CVE-2026-84428 is a high-severity authentication bypass vulnerability in fastify, published on 4 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-2026-84428 and fix it if it is affected.\n\nWhat it is: CVE-2026-84428 is a high-severity authentication bypass vulnerability in fastify, published on 4 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-2026-84428 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- fastify (npm): affected all versions; fixed in 5.12.2\n- fastify (npm): affected all versions; fixed in 5.12.2\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-2026-84428/ (Markdown: https://insights.sbomify.com/CVE-2026-84428/index.md)","id":"CVE-2026-84428","markdown":"https://insights.sbomify.com/CVE-2026-84428/index.md","name":"CVE-2026-84428","record":{"aliases":["CLSA-2026-1791634874","CLSA-2026-1792242589","GHSA-9q9j-q6p8-xq58","MINI-chf9-9mrc-3rhf"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"Node.js web framework","requires_auth":"none","summary":"An unauthenticated attacker can bypass conditional header validation checks in Fastify by exploiting incomplete case normalization in JSON Schema dependencies.","user_interaction":"not_required","vuln_class":"auth_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"openjs","cpe":[{"product":"fastify","vendor":"fastify"}],"cvss":{"score":7.5,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","version":"3.1"},"cwes":[{"id":"CWE-178","name":"Improper Handling of Case Sensitivity"}],"description":"fastify versions before 5.12.2 implement the case-insensitive nature of HTTP header names by lowercasing names in a route's header schema before compiling it, but the transformation is incomplete: it lowercases the properties keys and the root-level required array, and does not lowercase the trigger and dependent names inside the JSON Schema Draft 7 dependencies keyword. Because Node stores request header names in lowercase, a canonical-case dependency such as requiring an authentication header whenever a privileged-mode header is present never matches, and the presence assertion is silently skipped. An unauthenticated remote client can therefore send the header that activates a privileged branch while omitting the header the dependency was meant to require, bypassing the conditional check. Users should upgrade to fastify 5.12.2 or later.","ecosystems":["npm"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"fastify vulnerable to header validation bypass via incomplete schema case normalization","id":"CVE-2026-84428","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"npm","product":null,"products":[],"type":"auth_bypass","year":"2026"},"n_packages":2,"n_references":2,"next":{"headline":"Potential denial-of-service vulnerability in HTTP header parsing","id":"CVE-2026-84429"},"packages":[{"ecosystem":"npm","fixed":["5.12.2"],"introduced":["0"],"last_affected":[],"package":"fastify","purl":null,"source":"GHSA-9q9j-q6p8-xq58"},{"ecosystem":"npm","fixed":["5.12.2"],"introduced":["0"],"last_affected":[],"package":"fastify","purl":"pkg:npm/fastify","source":"GHSA-9q9j-q6p8-xq58"}],"prev":{"headline":"zhayujie CowAgent Bash Tool bash.py denial of service","id":"CVE-2026-84427"},"products":["fastify"],"published":"2026-09-04","related":[{"cvss_score":8.1,"headline":"fastify vulnerable to request body replacement via an async validation result collision","id":"CVE-2026-84504","kev_date_added":null,"published":"2026-09-04"},{"cvss_score":7.5,"headline":"fastify vulnerable to authentication bypass via malformed URLs reaching encapsulated not-found handlers","id":"CVE-2026-76169","kev_date_added":null,"published":"2026-09-04"},{"cvss_score":7.5,"headline":"fastify vulnerable to request validation bypass via skipped boolean false schemas","id":"CVE-2026-84469","kev_date_added":null,"published":"2026-09-04"},{"cvss_score":7.5,"headline":"fastify vulnerable to Body Schema Validation Bypass via Leading Space in Content-Type Header","id":"CVE-2026-33806","kev_date_added":null,"published":"2026-04-15"},{"cvss_score":7.5,"headline":"Fastify's Content-Type header tab character allows body validation bypass","id":"CVE-2026-25223","kev_date_added":null,"published":"2026-02-03"},{"cvss_score":7.5,"headline":"Fastify vulnerable to invalid content-type parsing, which could lead to validation bypass","id":"CVE-2025-32442","kev_date_added":null,"published":"2025-04-18"}],"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":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"yes","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-04","vendors":["fastify"]},"summary":"An unauthenticated attacker can bypass conditional header validation checks in Fastify by exploiting incomplete case normalization in JSON Schema dependencies.","url":"https://insights.sbomify.com/CVE-2026-84428/"}