CoSnitch: When Copilot Starts Snitching

This week’s CVE of the Week is CVE-2026-24301, also known as CoSnitch, an exfiltration method in Microsoft Copilot that could allow an unauthorized attacker to steal sensitive information and data. With a CVSS score of 8.8, deserves serious attention.

It is a combination of three different vulnerabilities that could allow an attacker to pull data from connected apps and other information available in the victim’s Copilot session.
CoSnitch is a unique vulnerability, Copilot surfaced its own flaws, researchers didn’t have to reverse-engineer it. The AI exposed the weakness during normal usage. Nowadays AI is widely used and can access many of our apps and personal data, including our calendars, emails and chats.

Three vulnerabilities made CoSnitch possible:

1. Automatic prompt execution: URL parameter combined with an undocumented parameter causes any attacker-supplied prompt without any user action.
2. Data exfiltration to external servers: The injected prompt can query the victim’s connected apps, encode the results into a URL, and exfiltrate them via Copilot’s built-in URL-fetch capability to the attacker-controlled webhook.
3. Persistent memory poisoning via web summarization: A crafted webpage, when summarized by Copilot and injects the attacker’s instructions into the victim’s permanent memory store. The injections survive password changes and session revoke too.

CoSnitch vulnerability was reported to Microsoft in December 2025, and patches were launched on August 18. 2026, as reports says no evidence that the attack has been exploited.

For detailed information, please check the following sites:
https://cvefeed.io/vuln/detail/CVE-2026-24301
https://www.varonis.com/blog/cosnitch

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