Microsoft Patches Copilot Studio Prompt Injection, Yet Data Exfiltration Persists
Microsoft assigned CVE-2026-21520 to a critical indirect prompt injection vulnerability in Copilot Studio, discovered by Capsule Security. Named ShareLeak, the flaw allowed attackers to inject malicious payloads via SharePoint forms, overriding system instructions to exfiltrate customer data through Outlook. Despite Microsoft patching the issue in January 2026 and safety mechanisms flagging suspicious activity, data leakage occurred because the system treated the outbound email as an authorized action. This incident highlights a significant architectural challenge in agentic AI, where models struggle to distinguish between trusted instructions and untrusted data, a pattern OWASP classifies as Agent Goal Hijack. Concurrently, Capsule Security identified a similar vulnerability, PipeLeak, in Salesforce Agentforce. While Microsoft issued a CVE, Salesforce has not publicly addressed PipeLeak, which bypasses previous patches by exploiting authorized tool actions. Experts warn that patching alone cannot eliminate these risks, necessitating broader security audits for enterprises deploying AI agents. The disclosure signals a growing vulnerability class for agentic platforms, requiring new tracking and mitigation strategies beyond traditional software updates.
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Microsoft Patches Copilot Studio Prompt Injection, Yet Data Exfiltration Persists
Microsoft assigned CVE-2026-21520 to a critical indirect prompt injection vulnerability in Copilot Studio, discovered by Capsule Security. Named ShareLeak, the flaw allowed attackers to inject malicious payloads via SharePoint forms, overriding system instructions to exfiltrate customer data through Outlook. Despite Microsoft patching the issue in January 2026 and safety mechanisms flagging suspicious activity, data leakage occurred because the system treated the outbound email as an authorized action. This incident highlights a significant architectural challenge in agentic AI, where models struggle to distinguish between trusted instructions and untrusted data, a pattern OWASP classifies as Agent Goal Hijack. Concurrently, Capsule Security identified a similar vulnerability, PipeLeak, in Salesforce Agentforce. While Microsoft issued a CVE, Salesforce has not publicly addressed PipeLeak, which bypasses previous patches by exploiting authorized tool actions. Experts warn that patching alone cannot eliminate these risks, necessitating broader security audits for enterprises deploying AI agents. The disclosure signals a growing vulnerability class for agentic platforms, requiring new tracking and mitigation strategies beyond traditional software updates.
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