CVE-2025-34072
CVE-2025-34072
9.3
CriticalPublished:
Last updated:
Source:disclosure@vulncheck.com
Deferred
CVSS Vector
v4.0- Attack Vector
- Network
- Attack Complexity
- Low
- Attack Requirements
- None
- Privileges Required
- None
- User Interaction
- None
- Confidentiality (Vulnerable)
- High
- Integrity (Vulnerable)
- None
- Availability (Vulnerable)
- None
- Confidentiality (Subsequent)
- High
- Integrity (Subsequent)
- High
- Availability (Subsequent)
- High
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.
References
disclosure@vulncheck.com
https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/disclosure@vulncheck.com
https://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration