{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "CVE-2026-56877 - Skillable",
          "vendor": "Cve",
          "versions": [
            {
              "status": "affected",
              "version": "unknown"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Greg via Fulldisclosure"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Skillable\u0027s SCORM lab launch endpoint validates a launch token but\nenforces per-user allocation limits using a browser-supplied userId\nthat is not bound to the validated token. An authenticated learner\ncan modify this identifier to bypass configured limits, launch\nconcurrent lab instances, and consume another learner\u0027s allocation.\nSkillable states that no fix is planned for the legacy SCORM launch\npath. CVE-2026-56877 was assigned by MITRE.\n\n\n1. Advisory information\n-----------------------\nTitle: CVE-2026-56877 - Skillable SCORM userId authorisation\nbypass\nAdvisory: https://github.com/GregDurys/security-advisories/tree/main/skillable\nCVE: CVE-2026-56877 (assigned; record publication pending)\nClass: CWE-639 (Authorization Bypass Through User-Controlled Key)\nCVSS: 6.5 (Medium) - AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\nDate: 2026-07-12\nAuthor: Greg Durys \u003chttps://payloadforge.io\u003e\n\n\n2. Affected software\n--------------------\nVendor: Skillable (formerly Learn on Demand Systems)\nService: Hosted SCORM lab provisioning (cloud service, no\non-premises deployment)\nEndpoint: scorm.skillable.com/scorm/launch\nTested: 2026-04-28 to 2026-05-03 (production endpoint, via the\nRed Team Ops course on the Zero Point Security platform)\nFix: None. The vendor states that no server-side identity\nvalidation will be added to the SCORM launch path.\nRemediation is migration to an API or LTI 1.3 launch\nintegration.\n\n\n3. Testing scope\n----------------\nAll validation was performed within a normal student workflow on\nthe Red Team Ops course. The bypass and the cross-user denial of\nservice were confirmed against the production endpoint. The\ncertification exam endpoint was not tested; Skillable subsequently\nconfirmed to an affected customer that the same weakness could\naffect exam allocations and could return details associated with\nanother learner\u0027s session.\n\n\n4. Summary\n----------\nThe SCORM launch request is assembled and initiated client-side.\nLoading a lab unit builds a launch URL and requests it from\nscorm.skillable.com with a SCORM token and userId as query\nparameters. Skillable validates the token sufficiently to authorise\nthe launch, then evaluates the per-user launch limit against the\nsupplied userId. The token is server-validated, while the userId is\nclient-controlled,\nand no binding between the two is enforced.\n\nThe userId accepts arbitrary strings with no format validation.\nValues with a non-hexadecimal character in an otherwise\nexpected-length identifier, and entirely fabricated structures, were\nboth accepted and provisioned lab instances. The same SCORM token\nlaunches labs under different userId values, demonstrating that the token does not bind the launch to the\nsupplied userId. The token remained unchanged\nacross the tested launches, indicating that it did not provide a\nuser-specific binding to the supplied userId.\n\n(a) Rate-limit bypass. Launching with a modified userId bypassed the\nper-user limit and provisioned a fresh LabInstanceId. Two\nconcurrent instances under different userId values were confirmed.\n\n(b) Cross-user denial of service. A consenting colleague\u0027s userId\nwas obtained through an authenticated learner enumeration vector\non the LMS. A lab launched under that userId consumed the\ncolleague\u0027s allocation. The colleague then attempted to launch\nthe same lab and was locked out, while other labs launched\nnormally.\n\n(c) Cost. Each instance provisions cloud VMs (typically a domain\ncontroller plus one to three machines, active 30 to 60 minutes)\nat the course provider\u0027s expense. An authenticated learner\nenumeration vector on the LMS would scale any of the above\nacross the enumerable enrolled population.\n\n\n5. Remediation\n--------------\nBind the launch to a server-validated learner identity, for example\nthrough a user-scoped signed token or server-to-server integration.\nDo not enforce per-user limits using an unverified browser-supplied\nuserId. Skillable states that it will not add this binding to the\nlegacy SCORM path and recommends migration to its API or LTI 1.3\nintegration.\n\n\n6. Disclosure timeline\n----------------------\n2026-04-28 Per-user rate-limit error observed; userId modification\nreturned a new LabInstanceId\n2026-04-29 Concurrent lab instances confirmed against a single\naccount\n2026-05-03 Cross-user denial of service confirmed with a consenting\nfellow student\n2026-05-08 Findings documented; Skillable support ticket #4043837\nraised; disclosure channel provided\n2026-05-11 Report submitted to Disclosures () skillable com (encrypted\narchive)\n2026-05-13 Skillable acknowledged receipt (Nat Shere, Manager,\nProduct Security)\n2026-05-19 CVE request submitted to MITRE (Skillable is not a CNA)\n2026-05-27 Status request to Skillable; no response\n2026-06-08 Second follow-up, restating the 60-day disclosure window\n(closing 2026-07-12)\n2026-06-10 Skillable responded that the issue is \"an inherent flaw\nin the SCORM technology\" and requested no disclosure\nwithout written permission\n2026-06-10 Pushback sent; open-ended embargo declined; 2026-07-12\ndate held\n2026-06-23 MITRE assigned CVE-2026-56877; coordinated disclosure\nremained under embargo until 2026-07-12\n2026-06-26 Skillable sent at least one affected customer an\nadvisory (\"SCORM-based lab launches and recommended\nmigration\"; no CVE, no CVSS), stating no server-side\nfix and recommending migration\n2026-06-26 Coordination update sent to Skillable\n2026-07-12 Advisory published\n\n\n7. Current status\n-----------------\nVendor fix: The vendor states that no fix is planned for\nthe SCORM launch path\nVendor remediation: Migration to an API or LTI 1.3 launch\nintegration\nCustomer communication: Sent to at least one affected customer on\n2026-06-26 (private notification, no CVE,\nno CVSS)\nCVE: CVE-2026-56877, assigned by the MITRE CNA of\nLast Resort\n\n\n8. References\n-------------\n- https://github.com/GregDurys/security-advisories/tree/main/skillable\n- https://www.cve.org/CVERecord?id=CVE-2026-56877\n- https://cwe.mitre.org/data/definitions/639.html\n- https://payloadforge.io/beyond-crto-skillable\n_______________________________________________\nSent through the Full Disclosure mailing list\nhttps://nmap.org/mailman/listinfo/fulldisclosure\nWeb Archives \u0026 RSS: https://seclists.org/fulldisclosure/"
        }
      ],
      "problemTypes": [
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          "descriptions": [
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              "description": "CWE-639",
              "lang": "en",
              "type": "CWE"
            }
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      "providerMetadata": {
        "dateUpdated": "2026-09-09T10:10:05Z",
        "orgId": "4e2abfbf-4a2a-4b76-a4e0-d77c18ba156c",
        "shortName": "VULNARCHIVE"
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      "references": [
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          "tags": [
            "technical-description"
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          "url": "https://vuln.freearchive.org/archive/full-disclosure/2026/Jul/20"
        },
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          "url": "https://seclists.org/fulldisclosure/2026/Jul/20"
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        },
        {
          "url": "https://github.com/GregDurys/security-advisories/tree/main/skillable"
        },
        {
          "url": "https://nmap.org/mailman/listinfo/fulldisclosure"
        },
        {
          "url": "https://payloadforge.io"
        },
        {
          "url": "https://payloadforge.io/beyond-crto-skillable"
        },
        {
          "url": "https://seclists.org/fulldisclosure/"
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        {
          "url": "https://www.cve.org/CVERecord?id=CVE-2026-56877"
        }
      ],
      "source": {
        "defect": [
          "https://seclists.org/fulldisclosure/2026/Jul/20"
        ],
        "discovery": "EXTERNAL"
      },
      "title": "CVE-2026-56877 - Skillable SCORM userId authorisation bypass",
      "x_gcve": [
        {
          "recordType": "advisory",
          "relationships": [],
          "vulnId": "GCVE-1988-2026-0097",
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            "evidenceScore": 8,
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    "assignerShortName": "VULNARCHIVE",
    "datePublished": "2026-09-07T13:20:22Z",
    "dateUpdated": "2026-09-09T10:10:05Z",
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