Anthropic Slack MCP Server Data Exfiltration via Link Unfurling
Published Jul 2, 2025
9.3
CRITICALCVSS 4.0
EPSS 0.43%
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.
Affected products
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Affected
- 0
Default status is the baseline for the product. Each version can override it (patched versions can be marked unaffected).
| Vendor | Product | Default status | Versions |
|---|---|---|---|
| Anthropic | Slack MCP Server | unaffected | Affected
|
No data.
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
References (3)
- https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/ third-party-advisorytechnical-descriptionexploit
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2025-19718 Advisory
- https://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration third-party-advisory
| Link | Providers | Tags |
|---|---|---|
| https://embracethered.com/blog/posts/2025/security-advisory-anthropic-slack-mcp-server-data-leakage/ | third-party-advisorytechnical-descriptionexploit | |
| https://euvd.enisa.europa.eu/vulnerability/EUVD-2025-19718 | Advisory | |
| https://vulncheck.com/advisories/anthropic-slack-mcp-server-data-exfiltration | third-party-advisory |
Change history (0)
No recorded changes yet.
CVE.org / MITRE
CISA Vulnrichment
Red Hat
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GitHub
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