{"answers":{"affected":"6 open source packages ship an affected version, including undici. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-18540 in the wild and no public exploit code.","fix":"Upgrade undici to a fixed version for your release line: 6.28.1, 7.29.1 or 8.10.2.","what":"CVE-2026-18540 is a low-severity vulnerability in Nodejs Undici, 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-2026-18540 and fix it if it is affected.\n\nWhat it is: CVE-2026-18540 is a low-severity vulnerability in Nodejs Undici, 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-2026-18540 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- undici (npm): affected all versions; fixed in 6.28.1\n- undici (npm): affected all versions; fixed in 6.28.1\n- undici (npm): affected from 7.0.0; fixed in 7.29.1\n- undici (npm): affected from 7.0.0; fixed in 7.29.1\n- undici (npm): affected from 8.0.0; fixed in 8.10.2\n- undici (npm): affected from 8.0.0; fixed in 8.10.2\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-2026-18540/ (Markdown: https://insights.sbomify.com/CVE-2026-18540/index.md)","id":"CVE-2026-18540","markdown":"https://insights.sbomify.com/CVE-2026-18540/index.md","name":"CVE-2026-18540","record":{"aliases":["AZL-99939","CLEANSTART-2026-FA02454","CLEANSTART-2026-OA04032","CLEANSTART-2026-QN51882","CLEANSTART-2026-RF59492","CLEANSTART-2026-UI28348","CLEANSTART-2026-ZP07254","CLSA-2026-1790755997","CLSA-2026-1790854818","CLSA-2026-1791666983","CLSA-2026-1791798691","CLSA-2026-1791908544","CLSA-2026-1791969425","CLSA-2026-1791969916","CLSA-2026-1792867309","CLSA-2026-1792867312","DEBIAN-CVE-2026-18540","ECHO-0f17-566d-0393","GHSA-r53p-7pc4-xj5r","MINI-2526-8vpg-2m9v","MINI-25rm-h2x3-ff2h","MINI-2xxw-7jvp-x8jq","MINI-6g4h-mjr8-fp9v","MINI-962f-xvpc-mgjj","MINI-9fq4-4hq5-pv42","MINI-9q58-g7xh-m5p8","MINI-c7pp-2j3g-w82x","MINI-fhj9-xh6v-x5r8","MINI-g2mj-f8h6-8c3f","MINI-g49j-h4rh-397g","MINI-j9x5-68jj-5368","MINI-m7fv-4p6m-v879","MINI-m7r7-7xpp-j9jf","MINI-m8qh-p4r8-fx65","MINI-mpcg-qf6r-2c4q","MINI-mx4r-87j2-9f4p","MINI-pq97-646j-35fh","MINI-qpr4-wf9m-44jp","MINI-v8qj-pj82-xhmp","MINI-vfch-6hx4-94x2","MINI-vqq2-p4mj-jxqm","ROOT-APP-NPM-CVE-2026-18540","UBUNTU-CVE-2026-18540"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["data_modify","security_bypass"],"network_reachable":"yes","non_default_config":true,"product_category":"Node.js HTTP client","requires_auth":"none","summary":"Attackers can cause HTTP response splitting in applications using undici's retry interceptor by controlling an upstream server, leading to potential cache poisoning or desynchronization.","user_interaction":"not_required","vuln_class":"other"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"openjs","cpe":[{"product":"undici","vendor":"nodejs"}],"cvss":{"score":3.7,"severity":"low","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-444","name":"Inconsistent Interpretation of HTTP Requests"}],"description":"undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.","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":"undici vulnerable to downstream response splitting via retry interceptor","id":"CVE-2026-18540","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"npm","product":"nodejs:undici","products":["nodejs:undici"],"type":"other","year":"2026"},"n_packages":6,"n_references":2,"next":{"headline":"IBM Planning Analytics Local is affected by security vulnerabilities","id":"CVE-2026-18541"},"packages":[{"ecosystem":"npm","fixed":["6.28.1"],"introduced":["0"],"last_affected":[],"package":"undici","purl":null,"source":"GHSA-r53p-7pc4-xj5r"},{"ecosystem":"npm","fixed":["6.28.1"],"introduced":["0"],"last_affected":[],"package":"undici","purl":"pkg:npm/undici","source":"GHSA-r53p-7pc4-xj5r"},{"ecosystem":"npm","fixed":["7.29.1"],"introduced":["7.0.0"],"last_affected":[],"package":"undici","purl":null,"source":"GHSA-r53p-7pc4-xj5r"},{"ecosystem":"npm","fixed":["7.29.1"],"introduced":["7.0.0"],"last_affected":[],"package":"undici","purl":"pkg:npm/undici","source":"GHSA-r53p-7pc4-xj5r"},{"ecosystem":"npm","fixed":["8.10.2"],"introduced":["8.0.0"],"last_affected":[],"package":"undici","purl":null,"source":"GHSA-r53p-7pc4-xj5r"},{"ecosystem":"npm","fixed":["8.10.2"],"introduced":["8.0.0"],"last_affected":[],"package":"undici","purl":"pkg:npm/undici","source":"GHSA-r53p-7pc4-xj5r"}],"prev":{"headline":"IBM Maximo Application Suite - Location Service for Esri Component Code Execution","id":"CVE-2026-18537"},"products":["undici"],"published":"2026-09-04","related":[{"cvss_score":7.5,"headline":"undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake","id":"CVE-2026-109855","kev_date_added":null,"published":"2026-10-15"},{"cvss_score":7.5,"headline":"undici vulnerable to Denial of Service via unhandled error on excessive content-encodings","id":"CVE-2026-109869","kev_date_added":null,"published":"2026-10-15"},{"cvss_score":7.5,"headline":"undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation","id":"CVE-2026-87018","kev_date_added":null,"published":"2026-10-15"},{"cvss_score":7.5,"headline":"undici vulnerable to Denial of Service via unrequested WebSocket subprotocol","id":"CVE-2026-19534","kev_date_added":null,"published":"2026-09-04"},{"cvss_score":7.5,"headline":"undici WebSocket client vulnerable to denial of service via fragment count bypass","id":"CVE-2026-12151","kev_date_added":null,"published":"2026-06-17"},{"cvss_score":7.5,"headline":"undici vulnerable to cross-origin request routing via SOCKS5 proxy pool reuse","id":"CVE-2026-6734","kev_date_added":null,"published":"2026-06-17"},{"cvss_score":7.5,"headline":"undici WebSocket client vulnerable to denial of service via cumulative fragment bypass","id":"CVE-2026-9675","kev_date_added":null,"published":"2026-06-17"}],"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":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-04","vendors":["undici"]},"summary":"Attackers can cause HTTP response splitting in applications using undici's retry interceptor by controlling an upstream server, leading to potential cache poisoning or desynchronization.","url":"https://insights.sbomify.com/CVE-2026-18540/"}