{"answers":{"affected":"2 open source packages ship an affected version, including yayson.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61534 exists.","fix":"Upgrade yayson to 4.3.0 or later.","what":"CVE-2026-61534 is a critical unsafe deserialization vulnerability in confetti yayson, published on 14 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-2026-61534 and fix it if it is affected.\n\nWhat it is: CVE-2026-61534 is a critical unsafe deserialization vulnerability in confetti yayson, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61534 exists.\n\nAffected packages and fixed versions:\n- yayson (npm): affected all versions; fixed in 4.3.0\n- yayson (npm): affected all versions; fixed in 4.3.0\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-2026-61534/ (Markdown: https://insights.sbomify.com/CVE-2026-61534/index.md)","id":"CVE-2026-61534","markdown":"https://insights.sbomify.com/CVE-2026-61534/index.md","name":"CVE-2026-61534","record":{"aliases":["GHSA-325j-mg25-8q58"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["denial_of_service","code_execution"],"network_reachable":"yes","non_default_config":false,"product_category":"JavaScript JSON API library","requires_auth":"none","summary":"Prototype pollution in Yayson allows attackers to corrupt Object.prototype via malicious JSON:API data, potentially leading to denial of service or code execution.","user_interaction":"not_required","vuln_class":"deserialization"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[],"cvss":{"score":9.1,"severity":"critical","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-1321","name":"Improperly Controlled Modification of Object Prototype Attributes"}],"description":"Yayson is a library for serializing and reading JSON API data in JavaScript. Prior to 4.3.0, Store and LegacyStore use attacker-controlled JSON:API type, id, and relationship names as keys in plain-object lookup tables in src/yayson/store.ts and src/yayson/legacy-store.ts. A document whose type is __proto__ causes model-cache writes to modify Object.prototype, with the attacker controlling the polluted property name through id and its value through attributes. The malicious type can also be supplied by an included resource, and LegacyStore is reachable when a configured types mapping resolves to __proto__. Unsafe relationship names including __proto__, constructor, and prototype provide additional document-derived member paths. The resulting process-wide prototype pollution can cause denial of service and logic corruption; authorization bypass or code execution depends on suitable gadgets in the consuming application. This issue is fixed in version 4.3.0.","ecosystems":["npm"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"Yayson: Prototype pollution in the Store/LegacyStore deserialization","id":"CVE-2026-61534","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"npm","product":null,"products":[],"type":"deserialization","year":"2026"},"n_packages":2,"n_references":4,"next":{"headline":"Banks: Unsafe importlib.import_module of attacker-controlled Tool.import_path in CompletionExtension allows RCE","id":"CVE-2026-61536"},"packages":[{"ecosystem":"npm","fixed":["4.3.0"],"introduced":["0"],"last_affected":[],"package":"yayson","purl":null,"source":"GHSA-325j-mg25-8q58"},{"ecosystem":"npm","fixed":["4.3.0"],"introduced":["0"],"last_affected":[],"package":"yayson","purl":"pkg:npm/yayson","source":"GHSA-325j-mg25-8q58"}],"prev":{"headline":"Endatix: Blind second-order SSRF via anonymous form-submission file URLs (`SubmissionFileExtractor`)","id":"CVE-2026-61529"},"products":["yayson"],"published":"2026-09-14","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":"yes","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-14","vendors":["confetti"]},"summary":"Prototype pollution in Yayson allows attackers to corrupt Object.prototype via malicious JSON:API data, potentially leading to denial of service or code execution.","url":"https://insights.sbomify.com/CVE-2026-61534/"}