CVE-2025-34072

CRITICAL

Anthropic's Slack Model Context Protocol Server - Info Disclosure

Title source: llm
STIX 2.1

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 (2)

Core 2
Core References
Various Sources third-party-advisory technical-description exploit
https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/

Scores

CVSS v4 9.3
EPSS 0.0037
EPSS Percentile 28.7%
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

CISA SSVC

Vulnrichment
Exploitation poc
Automatable no
Technical Impact partial

Details

CWE
CWE-20 CWE-200
Status published
Products (1)
Anthropic/Slack MCP Server
Published Jul 02, 2025
Tracked Since Feb 18, 2026