CVE-2025-34072

Public Exploit
Anthropic Slack MCP Server Data Exfiltration via Link Unfurling

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.

Category

9.3
CVSS
Severity: Critical
CVSS 4.0 •
EPSS 0.08%
Third-Party Advisory embracethered.com Third-Party Advisory vulncheck.com
Affected: Anthropic Slack MCP Server
Published at:
Updated at:

References

Link Tags
https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/ technical description third party advisory exploit
https://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration third party advisory

Frequently Asked Questions

What is the severity of CVE-2025-34072?
CVE-2025-34072 has been scored as a critical severity vulnerability.
How to fix CVE-2025-34072?
To fix CVE-2025-34072, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-34072 being actively exploited in the wild?
It is possible that CVE-2025-34072 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-34072?
CVE-2025-34072 affects Anthropic Slack MCP Server.
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