CVE-2026-50029 (GCVE-0-2026-50029)
Vulnerability from cvelistv5
Published
2026-08-14 19:08
Modified
2026-08-17 19:34
CWE
Summary
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.
Impacted products
Vendor Product Version
sunnyadn js-toml Version: < 1.1.2
Create a notification for this product.
Show details on NVD website


{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-50029",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-17T19:34:09.834226Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-17T19:34:15.876Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/sunnyadn/js-toml/security/advisories/GHSA-m34p-749j-x6m6"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "js-toml",
          "vendor": "sunnyadn",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.1.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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 \u2014 `false`, `0`, `0n`, `0.0`, `-0`, or `\"\"` \u2014 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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-697",
              "description": "CWE-697: Incorrect Comparison",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-14T19:08:54.941Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/sunnyadn/js-toml/security/advisories/GHSA-m34p-749j-x6m6",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/sunnyadn/js-toml/security/advisories/GHSA-m34p-749j-x6m6"
        },
        {
          "name": "https://github.com/sunnyadn/js-toml/commit/e0504fa5d3dcde2d1d588c9001c24b7b700beeeb",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/sunnyadn/js-toml/commit/e0504fa5d3dcde2d1d588c9001c24b7b700beeeb"
        },
        {
          "name": "https://github.com/sunnyadn/js-toml/releases/tag/v1.1.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/sunnyadn/js-toml/releases/tag/v1.1.2"
        }
      ],
      "source": {
        "advisory": "GHSA-m34p-749j-x6m6",
        "discovery": "UNKNOWN"
      },
      "title": "js-toml has silent type confusion via falsy-primitive duplicate-key bypass"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-50029",
    "datePublished": "2026-08-14T19:08:54.941Z",
    "dateReserved": "2026-06-02T22:46:02.580Z",
    "dateUpdated": "2026-08-17T19:34:15.876Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-50029\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-17T19:34:09.834226Z\"}}}], \"references\": [{\"url\": \"https://github.com/sunnyadn/js-toml/security/advisories/GHSA-m34p-749j-x6m6\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-17T19:33:46.748Z\"}}], \"cna\": {\"title\": \"js-toml has silent type confusion via falsy-primitive duplicate-key bypass\", \"source\": {\"advisory\": \"GHSA-m34p-749j-x6m6\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 5.3, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N\", \"integrityImpact\": \"LOW\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"sunnyadn\", \"product\": \"js-toml\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 1.1.2\"}]}], \"references\": [{\"url\": \"https://github.com/sunnyadn/js-toml/security/advisories/GHSA-m34p-749j-x6m6\", \"name\": \"https://github.com/sunnyadn/js-toml/security/advisories/GHSA-m34p-749j-x6m6\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/sunnyadn/js-toml/commit/e0504fa5d3dcde2d1d588c9001c24b7b700beeeb\", \"name\": \"https://github.com/sunnyadn/js-toml/commit/e0504fa5d3dcde2d1d588c9001c24b7b700beeeb\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/sunnyadn/js-toml/releases/tag/v1.1.2\", \"name\": \"https://github.com/sunnyadn/js-toml/releases/tag/v1.1.2\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"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 \\u2014 `false`, `0`, `0n`, `0.0`, `-0`, or `\\\"\\\"` \\u2014 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.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-697\", \"description\": \"CWE-697: Incorrect Comparison\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-08-14T19:08:54.941Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-50029\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-17T19:34:15.876Z\", \"dateReserved\": \"2026-06-02T22:46:02.580Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-08-14T19:08:54.941Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.


Loading…

Loading…

Loading…

Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.


Loading…

Loading…