CVE-2025-34072

critical · 9.3

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.

9.3

CVSS

0.4%

EPSS (exploit prob.)

31st

EPSS percentile

2025-07-02

Published

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

Weaknesses

CWE-20CWE-200

References

https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/
https://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2025-34072