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.
History

Wed, 02 Jul 2025 21:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 02 Jul 2025 14:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Anthropic Slack MCP Server Data Exfiltration via Link Unfurling
Weaknesses CWE-20
CWE-200
References
Metrics cvssV4_0

{'score': 9.3, 'vector': '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2025-07-02T13:46:31.554Z

Updated: 2025-07-02T20:29:17.261Z

Reserved: 2025-04-15T19:15:22.550Z

Link: CVE-2025-34072

cve-icon Vulnrichment

Updated: 2025-07-02T20:29:13.541Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-07-02T14:15:24.817

Modified: 2025-07-03T15:13:53.147

Link: CVE-2025-34072

cve-icon Redhat

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