---
title: "M365 Copilot SearchLeak: Your prompt injection attack surface just got bigger"
url: https://daily.dev/posts/m365-copilot-searchleak-your-prompt-injection-attack-surface-just-got-bigger-rtnadamjv
source_url: https://www.csoonline.com/article/4186970/m365-copilot-searchleak-your-prompt-injection-attack-surface-just-got-bigger.html
type: article
source: "CSO Online"
published: 2026-06-19T07:03:28.350Z
updated: 2026-06-19T07:05:55.083Z
tags: ["security", "microsoft", "llm", "prompt-injection", "data-exfiltration"]
reading_time: 6
upvotes: 0
comments: 0
language: en
---

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# M365 Copilot SearchLeak: Your prompt injection attack surface just got bigger

**[CSO Online](https://daily.dev/sources/csoonline)** · 6 min read · 0 upvotes · 0 comments

## Summary

Varonis Threat Labs disclosed a proof-of-concept attack called SearchLeak targeting Microsoft 365 Copilot Enterprise Search. The attack chains three weaknesses: a parameter-to-prompt (P2P) injection via the URL's ?q= parameter, a race condition that allows HTML rendering during the model's thinking phase before output sanitization kicks in, and a CSP bypass using Bing Image Search as a proxy to exfiltrate data to an attacker-controlled server. The result is that a single crafted link clicked by a victim can leak sensitive corporate data — including emails, SharePoint documents, and even 2FA codes — without any authentication on the attacker's side. Microsoft patched the critical vulnerability server-side. The post also highlights P2P injection as a broader emerging attack class affecting other AI-powered web services, and offers mitigation guidance for developers and security teams.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://www.csoonline.com/article/4186970/m365-copilot-searchleak-your-prompt-injection-attack-surface-just-got-bigger.html>

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---

Tags: [#security](https://daily.dev/tags/security), [#microsoft](https://daily.dev/tags/microsoft), [#llm](https://daily.dev/tags/llm), [#prompt-injection](https://daily.dev/tags/prompt-injection), [#data-exfiltration](https://daily.dev/tags/data-exfiltration)

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