{"cve":"CVE-2026-50029","nvd":{"published":"2026-08-14T19:17:18.980","modified":"2026-09-18T20:09:01.757","status":"Deferred","description":"js-toml is a TOML parser for JavaScript, Prior to version 1.1.2, the interpreter checks whether a key already exists in a parser-built container with `if (object[key])` instead of `if (key in object)`. When the prior value is a falsy primitive — `false`, `0`, `0n`, `0.0`, `-0`, or `\"\"` — the duplicate-key branch is skipped and the value is silently overwritten by a later sub-table, dotted-key sub-table, or array-of-tables sharing the same name. Per the TOML 1.0.0 spec (\"Defining a key multiple times is invalid\"; \"You cannot define any key or table more than once\"), this should be a parse error. The result is structural type confusion of attacker-named keys in the value returned by `load()`. A boolean-typed `false` (or numeric `0`) becomes a truthy object. Host applications that gate behavior on `if (config.flag)`, `if (!user.banned)`, `if (config.allowDelete)`, or `if (config.publicMode)` will silently take the truthy branch. This is distinct from GHSA-65fc-cr5f-v7r2 (the 1.0.2 prototype-pollution fix). `Object.prototype` is not polluted. The `Object.create(null)` mitigation from 1.0.2 is intact; the bug here is in the duplicate-key state machine, not in container construction. Version 1.1.2 patches the incorrect comparison.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":5.3},"cwes":["CWE-697"],"references":["https://github.com/sunnyadn/js-toml/commit/e0504fa5d3dcde2d1d588c9001c24b7b700beeeb","https://github.com/sunnyadn/js-toml/releases/tag/v1.1.2","https://github.com/sunnyadn/js-toml/security/advisories/GHSA-m34p-749j-x6m6","https://github.com/sunnyadn/js-toml/security/advisories/GHSA-m34p-749j-x6m6"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:48:17.459049833+00:00"},"epss":{"cve":"CVE-2026-50029","score":0.00398,"percentile":0.34071,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-m34p-749j-x6m6","url":"https://osv.dev/vulnerability/GHSA-m34p-749j-x6m6","summary":"js-toml has silent type confusion via falsy-primitive duplicate-key bypass","modified":"2026-07-21T17:30:26.096074019Z","packages":[{"ecosystem":"npm","name":"js-toml","purl":"pkg:npm/js-toml","ranges":["<1.1.2"],"fixed":["1.1.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}