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    2 vulnerabilities by leshchenko1979

    CVE-2026-52830 (GCVE-0-2026-52830)

    Vulnerability from nvd – Published: 2026-07-02 20:39 – Updated: 2026-07-02 20:39
    VLAI
    Title
    fast-mcp-telegram: Bearer token path traversal bypasses reserved Telegram session protection
    Summary
    fast-mcp-telegram is a Telegram MCP Server. Prior to 0.19.1, fast-mcp-telegram validates HTTP Bearer tokens by joining the raw token string into a session-file path. The verifier rejects the exact reserved token telegram, but it does not reject path separators or normalize the path before checking whether the session file exists. A remote HTTP client can therefore authenticate as the default legacy session with a token such as ../fast-mcp-telegram/telegram when the documented default session file ~/.config/fast-mcp-telegram/telegram.session exists. This bypasses the reserved session name control that is intended to prevent HTTP multi-user sessions from colliding with the default stdio or legacy account. With account-prefixed MCP tools enabled, the attacker still sees and calls the prefixed tools for the default account, so the prefix middleware does not stop the session selection bypass. This vulnerability is fixed in 0.19.1.
    Severity
    9.4 (Critical)
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
    CWE
    • CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
    • CWE-287 - Improper Authentication
    Assigner
    References
    Impacted products
    Show details on NVD website
    To clipboard 

    {
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "fast-mcp-telegram",
          "vendor": "leshchenko1979",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.19.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "fast-mcp-telegram is a Telegram MCP Server. Prior to 0.19.1, fast-mcp-telegram validates HTTP Bearer tokens by joining the raw token string into a session-file path. The verifier rejects the exact reserved token telegram, but it does not reject path separators or normalize the path before checking whether the session file exists. A remote HTTP client can therefore authenticate as the default legacy session with a token such as ../fast-mcp-telegram/telegram when the documented default session file ~/.config/fast-mcp-telegram/telegram.session exists. This bypasses the reserved session name control that is intended to prevent HTTP multi-user sessions from colliding with the default stdio or legacy account. With account-prefixed MCP tools enabled, the attacker still sees and calls the prefixed tools for the default account, so the prefix middleware does not stop the session selection bypass. This vulnerability is fixed in 0.19.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 9.4,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-287",
              "description": "CWE-287: Improper Authentication",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-02T20:39:35.927Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://web.archive.org/web/20250926152207/https://github.com/leshchenko1979/fast-mcp-telegram",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://web.archive.org/web/20250926152207/https://github.com/leshchenko1979/fast-mcp-telegram"
        },
        {
          "name": "https://github.com/advisories/GHSA-rxw2-pc8j-vxwm",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/advisories/GHSA-rxw2-pc8j-vxwm"
        }
      ],
      "source": {
        "advisory": "GHSA-rxw2-pc8j-vxwm",
        "discovery": "UNKNOWN"
      },
      "title": "fast-mcp-telegram: Bearer token path traversal bypasses reserved Telegram session protection"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-52830",
    "datePublished": "2026-07-02T20:39:35.927Z",
    "dateReserved": "2026-06-08T18:11:06.662Z",
    "dateUpdated": "2026-07-02T20:39:35.927Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

    CVE-2026-52830 (GCVE-0-2026-52830)

    Vulnerability from cvelistv5 – Published: 2026-07-02 20:39 – Updated: 2026-07-02 20:39
    VLAI
    Title
    fast-mcp-telegram: Bearer token path traversal bypasses reserved Telegram session protection
    Summary
    fast-mcp-telegram is a Telegram MCP Server. Prior to 0.19.1, fast-mcp-telegram validates HTTP Bearer tokens by joining the raw token string into a session-file path. The verifier rejects the exact reserved token telegram, but it does not reject path separators or normalize the path before checking whether the session file exists. A remote HTTP client can therefore authenticate as the default legacy session with a token such as ../fast-mcp-telegram/telegram when the documented default session file ~/.config/fast-mcp-telegram/telegram.session exists. This bypasses the reserved session name control that is intended to prevent HTTP multi-user sessions from colliding with the default stdio or legacy account. With account-prefixed MCP tools enabled, the attacker still sees and calls the prefixed tools for the default account, so the prefix middleware does not stop the session selection bypass. This vulnerability is fixed in 0.19.1.
    Severity
    9.4 (Critical)
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
    CWE
    • CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
    • CWE-287 - Improper Authentication
    Assigner
    References
    Impacted products
    Show details on NVD website
    To clipboard 

    {
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "fast-mcp-telegram",
          "vendor": "leshchenko1979",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.19.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "fast-mcp-telegram is a Telegram MCP Server. Prior to 0.19.1, fast-mcp-telegram validates HTTP Bearer tokens by joining the raw token string into a session-file path. The verifier rejects the exact reserved token telegram, but it does not reject path separators or normalize the path before checking whether the session file exists. A remote HTTP client can therefore authenticate as the default legacy session with a token such as ../fast-mcp-telegram/telegram when the documented default session file ~/.config/fast-mcp-telegram/telegram.session exists. This bypasses the reserved session name control that is intended to prevent HTTP multi-user sessions from colliding with the default stdio or legacy account. With account-prefixed MCP tools enabled, the attacker still sees and calls the prefixed tools for the default account, so the prefix middleware does not stop the session selection bypass. This vulnerability is fixed in 0.19.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 9.4,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-287",
              "description": "CWE-287: Improper Authentication",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-02T20:39:35.927Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://web.archive.org/web/20250926152207/https://github.com/leshchenko1979/fast-mcp-telegram",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://web.archive.org/web/20250926152207/https://github.com/leshchenko1979/fast-mcp-telegram"
        },
        {
          "name": "https://github.com/advisories/GHSA-rxw2-pc8j-vxwm",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/advisories/GHSA-rxw2-pc8j-vxwm"
        }
      ],
      "source": {
        "advisory": "GHSA-rxw2-pc8j-vxwm",
        "discovery": "UNKNOWN"
      },
      "title": "fast-mcp-telegram: Bearer token path traversal bypasses reserved Telegram session protection"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-52830",
    "datePublished": "2026-07-02T20:39:35.927Z",
    "dateReserved": "2026-06-08T18:11:06.662Z",
    "dateUpdated": "2026-07-02T20:39:35.927Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}