Chainlit < 2.10.1 Session Hijacking via WebSocket Session Restoration

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-56104",
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "dateUpdated": "2026-06-22T16:06:48.051Z",
    "dateReserved": "2026-06-18T19:15:10.650Z",
    "datePublished": "2026-06-22T14:17:52.640Z",
    "state": "PUBLISHED"
  },
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        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
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        "dateUpdated": "2026-06-22T14:17:52.640Z"
      },
      "datePublic": "2026-05-24T00:00:00.000Z",
      "title": "Chainlit < 2.10.1 Session Hijacking via WebSocket Session Restoration",
      "descriptions": [
        {
          "lang": "en",
          "value": "Chainlit before 2.10.1 contains a session hijacking vulnerability that allows unauthenticated attackers to restore and inherit authenticated user sessions by presenting a valid sessionId during WebSocket session restoration without ownership verification. Attackers can exploit the restore_existing_session path to assume a victim's permissions and roles, enabling unauthorized invocation of tools and access to data restricted to the authenticated victim."
        }
      ],
      "affected": [
        {
          "vendor": "Chainlit",
          "product": "chainlit",
          "repo": "https://github.com/Chainlit/chainlit",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "2.10.1"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "Missing Authorization",
              "cweId": "CWE-862",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/Chainlit/chainlit/releases/tag/2.10.1",
          "name": "Release Notes",
          "tags": [
            "release-notes"
          ]
        },
        {
          "url": "https://github.com/Chainlit/chainlit/pull/2857",
          "name": "Pull Request",
          "tags": [
            "issue-tracking"
          ]
        },
        {
          "url": "https://github.com/Chainlit/chainlit/commit/5effb664f1e0af4a4f0a42fe63ea979676039a7f",
          "name": "Patch Commit",
          "tags": [
            "patch"
          ]
        },
        {
          "url": "https://www.vulncheck.com/advisories/chainlit-session-hijacking-via-websocket-session-restoration",
          "tags": [
            "third-party-advisory"
          ]
        }
      ],
      "metrics": [
        {
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
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          "format": "CVSS",
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          "cvssV3_1": {
            "version": "3.1",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "attackVector": "NETWORK",
            "attackComplexity": "HIGH",
            "privilegesRequired": "NONE",
            "userInteraction": "NONE",
            "scope": "UNCHANGED",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "availabilityImpact": "NONE",
            "baseScore": 7.4,
            "baseSeverity": "HIGH"
          }
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Tanguy Snoeck",
          "type": "finder"
        }
      ],
      "tags": [
        "x_open-source"
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    "adp": [
      {
        "providerMetadata": {
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          "shortName": "CISA-ADP",
          "dateUpdated": "2026-06-22T16:06:48.051Z"
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        "title": "CISA ADP Vulnrichment",
        "metrics": [
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}