CVE-2025-34072 (GCVE-0-2025-34072)
Vulnerability from cvelistv5
Published
2025-07-02 13:46
Modified
2025-07-02 20:29
Severity ?
9.3 (Critical) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H
CWE
  • CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-20 - Improper Input Validation
Summary
A data exfiltration vulnerability exists in Anthropic’s deprecated Slack Model Context Protocol (MCP) Server via automatic link unfurling. When an AI agent using the Slack MCP Server processes untrusted data, it can be manipulated to generate messages containing attacker-crafted hyperlinks embedding sensitive data. Slack’s link preview bots (e.g., Slack-LinkExpanding, Slackbot, Slack-ImgProxy) will then issue outbound requests to the attacker-controlled URL, resulting in zero-click exfiltration of private data.
References
disclosure@vulncheck.comhttps://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/
disclosure@vulncheck.comhttps://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration
Impacted products
Vendor Product Version
Anthropic Slack MCP Server Version: 0
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-34072",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-07-02T20:29:08.961760Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-07-02T20:29:17.261Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "modules": [
            "Anthropic Slack MCP Server",
            "Message content (post/reply body)"
          ],
          "product": "Slack MCP Server",
          "vendor": "Anthropic",
          "versions": [
            {
              "status": "affected",
              "version": "0"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "wunderwuzzi of Embrace The Red"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "A data exfiltration vulnerability exists in Anthropic\u2019s deprecated Slack Model Context Protocol (MCP) Server via automatic link unfurling. When an AI agent using the Slack MCP Server processes untrusted data, it can be manipulated to generate messages containing attacker-crafted hyperlinks embedding sensitive data. Slack\u2019s link preview bots (e.g., \u003ccode\u003eSlack-LinkExpanding\u003c/code\u003e, \u003ccode\u003eSlackbot\u003c/code\u003e, \u003ccode\u003eSlack-ImgProxy\u003c/code\u003e) will then issue outbound requests to the attacker-controlled URL, resulting in zero-click exfiltration of private data."
            }
          ],
          "value": "A data exfiltration vulnerability exists in Anthropic\u2019s deprecated Slack Model Context Protocol (MCP) Server via automatic link unfurling. When an AI agent using the Slack MCP Server processes untrusted data, it can be manipulated to generate messages containing attacker-crafted hyperlinks embedding sensitive data. Slack\u2019s link preview bots (e.g., Slack-LinkExpanding, Slackbot, Slack-ImgProxy) will then issue outbound requests to the attacker-controlled URL, resulting in zero-click exfiltration of private data."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-34",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-34 HTTP Response Splitting"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 9.3,
            "baseSeverity": "CRITICAL",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "HIGH",
            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-200",
              "description": "CWE-200 Exposure of Sensitive Information to an Unauthorized Actor",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-20",
              "description": "CWE-20 Improper Input Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-07-02T13:46:31.554Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "tags": [
            "third-party-advisory",
            "technical-description",
            "exploit"
          ],
          "url": "https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Anthropic Slack MCP Server Data Exfiltration via Link Unfurling",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2025-34072",
    "datePublished": "2025-07-02T13:46:31.554Z",
    "dateReserved": "2025-04-15T19:15:22.550Z",
    "dateUpdated": "2025-07-02T20:29:17.261Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-34072\",\"sourceIdentifier\":\"disclosure@vulncheck.com\",\"published\":\"2025-07-02T14:15:24.817\",\"lastModified\":\"2025-07-03T15:13:53.147\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"A data exfiltration vulnerability exists in Anthropic\u2019s deprecated Slack Model Context Protocol (MCP) Server via automatic link unfurling. When an AI agent using the Slack MCP Server processes untrusted data, it can be manipulated to generate messages containing attacker-crafted hyperlinks embedding sensitive data. Slack\u2019s link preview bots (e.g., Slack-LinkExpanding, Slackbot, Slack-ImgProxy) will then issue outbound requests to the attacker-controlled URL, resulting in zero-click exfiltration of private data.\"},{\"lang\":\"es\",\"value\":\"Existe una vulnerabilidad de exfiltraci\u00f3n de datos en el servidor obsoleto del Protocolo de Contexto de Modelo (MCP) de Slack de Anthropic mediante el despliegue autom\u00e1tico de enlaces. Cuando un agente de IA que utiliza el servidor MCP de Slack procesa datos no confiables, estos pueden manipularse para generar mensajes con hiperv\u00ednculos manipulados por el atacante que integran datos confidenciales. Los bots de previsualizaci\u00f3n de enlaces de Slack (p. ej., Slack-LinkExpanding, Slackbot, Slack-ImgProxy) emiten solicitudes salientes a la URL controlada por el atacante, lo que resulta en la exfiltraci\u00f3n de datos privados sin necesidad de hacer clic.\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":9.3,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"HIGH\",\"subIntegrityImpact\":\"HIGH\",\"subAvailabilityImpact\":\"HIGH\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-20\"},{\"lang\":\"en\",\"value\":\"CWE-200\"}]}],\"references\":[{\"url\":\"https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration\",\"source\":\"disclosure@vulncheck.com\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-34072\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2025-07-02T20:29:08.961760Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-07-02T20:29:13.541Z\"}}], \"cna\": {\"title\": \"Anthropic Slack MCP Server Data Exfiltration via Link Unfurling\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"wunderwuzzi of Embrace The Red\"}], \"impacts\": [{\"capecId\": \"CAPEC-34\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"CAPEC-34 HTTP Response Splitting\"}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 9.3, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"CRITICAL\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"HIGH\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"HIGH\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"HIGH\", \"vulnConfidentialityImpact\": \"HIGH\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"vendor\": \"Anthropic\", \"modules\": [\"Anthropic Slack MCP Server\", \"Message content (post/reply body)\"], \"product\": \"Slack MCP Server\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\"}], \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/\", \"tags\": [\"third-party-advisory\", \"technical-description\", \"exploit\"]}, {\"url\": \"https://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration\", \"tags\": [\"third-party-advisory\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"A data exfiltration vulnerability exists in Anthropic\\u2019s deprecated Slack Model Context Protocol (MCP) Server via automatic link unfurling. When an AI agent using the Slack MCP Server processes untrusted data, it can be manipulated to generate messages containing attacker-crafted hyperlinks embedding sensitive data. Slack\\u2019s link preview bots (e.g., Slack-LinkExpanding, Slackbot, Slack-ImgProxy) will then issue outbound requests to the attacker-controlled URL, resulting in zero-click exfiltration of private data.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"A data exfiltration vulnerability exists in Anthropic\\u2019s deprecated Slack Model Context Protocol (MCP) Server via automatic link unfurling. When an AI agent using the Slack MCP Server processes untrusted data, it can be manipulated to generate messages containing attacker-crafted hyperlinks embedding sensitive data. Slack\\u2019s link preview bots (e.g., \u003ccode\u003eSlack-LinkExpanding\u003c/code\u003e, \u003ccode\u003eSlackbot\u003c/code\u003e, \u003ccode\u003eSlack-ImgProxy\u003c/code\u003e) will then issue outbound requests to the attacker-controlled URL, resulting in zero-click exfiltration of private data.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-200\", \"description\": \"CWE-200 Exposure of Sensitive Information to an Unauthorized Actor\"}]}, {\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-20\", \"description\": \"CWE-20 Improper Input Validation\"}]}], \"providerMetadata\": {\"orgId\": \"83251b91-4cc7-4094-a5c7-464a1b83ea10\", \"shortName\": \"VulnCheck\", \"dateUpdated\": \"2025-07-02T13:46:31.554Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-34072\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2025-07-02T20:29:17.261Z\", \"dateReserved\": \"2025-04-15T19:15:22.550Z\", \"assignerOrgId\": \"83251b91-4cc7-4094-a5c7-464a1b83ea10\", \"datePublished\": \"2025-07-02T13:46:31.554Z\", \"assignerShortName\": \"VulnCheck\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.1"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




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.
  • 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.