{"answers":{"affected":"2 open source packages ship an affected version, including fast-uri.","exploited":"There is no known exploitation of CVE-2026-86818 in the wild and no public exploit code.","fix":"Upgrade fast-uri to 4.1.5 or later.","what":"CVE-2026-86818 is a medium-severity vulnerability in fast-uri, published on 15 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-2026-86818 and fix it if it is affected.\n\nWhat it is: CVE-2026-86818 is a medium-severity vulnerability in fast-uri, published on 15 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-2026-86818 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- fast-uri (npm): affected from 4.1.3; fixed in 4.1.5\n- fast-uri (npm): affected from 4.1.3; fixed in 4.1.5\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-2026-86818/ (Markdown: https://insights.sbomify.com/CVE-2026-86818/index.md)","id":"CVE-2026-86818","markdown":"https://insights.sbomify.com/CVE-2026-86818/index.md","name":"CVE-2026-86818","record":{"aliases":["DEBIAN-CVE-2026-86818","GHSA-jvvf-x445-j334","MINI-2pc9-58jr-mjmf","UBUNTU-CVE-2026-86818"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["data_modify","security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"Node.js URI parser","requires_auth":"none","summary":"Attackers can inject malicious recipients or headers into mailto URIs by exploiting percent-encoding desynchronization in the fast-uri parser.","user_interaction":"not_required","vuln_class":"other"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"openjs","cpe":[],"cvss":{"score":4.8,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-436","name":"Interpretation Conflict"},{"id":"CWE-172","name":"Improper Encoding or Decoding of Data"}],"description":"fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv, that added a mailto scheme parser in version 4.1.3. In versions 4.1.3 and 4.1.4, the mailto parser compares each query field name to the reserved names to, subject, and body while the name is still percent-encoded, and decodes it only when storing it as a generic header, so a percent-encoded spelling of a reserved field name is not recognized as that field at parse time but is re-emitted as the literal field name when the parsed URI is serialized. An application that validates, logs, or displays the recipient list from the first parse and then serializes the URI and sends it can silently gain an attacker-chosen recipient, and the subject and body fields can be smuggled across the same roundtrip. The issue is fixed in fast-uri 4.1.5, and users should upgrade to 4.1.5 or later. As a workaround, do not act on a mailto URI that fast-uri has re-serialized without first decoding and re-validating its recipient, subject, and body fields.","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":"fast-uri vulnerable to mailto header injection via percent-encoded field-name desynchronization","id":"CVE-2026-86818","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"npm","product":null,"products":[],"type":"other","year":"2026"},"n_packages":2,"n_references":2,"next":{"headline":"Waves Central local privilege escalation via Improper XPC Client Authentication in macOS","id":"CVE-2026-86819"},"packages":[{"ecosystem":"npm","fixed":["4.1.5"],"introduced":["4.1.3"],"last_affected":[],"package":"fast-uri","purl":null,"source":"GHSA-jvvf-x445-j334"},{"ecosystem":"npm","fixed":["4.1.5"],"introduced":["4.1.3"],"last_affected":[],"package":"fast-uri","purl":"pkg:npm/fast-uri","source":"GHSA-jvvf-x445-j334"}],"prev":{"headline":"Information disclosure in Five Star Business Profile and Schema","id":"CVE-2026-86817"},"products":["fast-uri"],"published":"2026-09-15","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":"2026-09-15","vendors":["fast-uri"]},"summary":"Attackers can inject malicious recipients or headers into mailto URIs by exploiting percent-encoding desynchronization in the fast-uri parser.","url":"https://insights.sbomify.com/CVE-2026-86818/"}