CVE-2025-34072Public exploitNetwork attack vector

Data exfiltration via automatic link unfurling

Published Jul 2, 2025 · Updated Jul 2, 2025

Data exfiltration in Anthropic Slack MCP Server allows remote attackers to leak private data through automatic Slack link previews. The post and reply handlers send attacker-influenced text to chat.postMessage without disabling link or media unfurling, causing Slack preview bots to request secret-bearing URLs. Exploitation requires an agent with private-data access to process untrusted content and post without supervision; the consequence is disclosure to an attacker-controlled server.

CVSS severity9.3
Critical
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Data exfiltration in Anthropic Slack MCP Server allows remote attackers to leak private data through automatic Slack link previews. The post and reply handlers send attacker-influenced text to chat.postMessage without disabling link or media unfurling, causing Slack preview bots to request secret-bearing URLs. Exploitation requires an agent with private-data access to process untrusted content and post without supervision; the consequence is disclosure to an attacker-controlled server.

The record

CVE
CVE-2025-34072
Published
Jul 2, 2025
Updated
Jul 2, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-200, CWE-20, T1020
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 2, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 2, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
CWE-20Improper Input Validation
T1020Automated Exfiltration

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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