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German government CERT advisories reported multiple vulnerabilities affecting Microsoft 365 Copilot and Microsoft 365 Copilot Business Chat, including flaws that can lead to information disclosure. One advisory specifically identified Business Chat as vulnerable to several issues that could expose data, while a later advisory expanded the scope to Microsoft 365 Copilot more broadly.
The notices indicate that organizations using Microsoft’s AI-assisted productivity features may face risk from weaknesses in how Copilot components handle or expose information. Security teams should review Microsoft guidance and product-specific remediation for affected Copilot deployments, with particular attention to Business Chat instances where disclosure-related impact was explicitly highlighted.
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dCERT published Advisory 2026-1641 describing multiple vulnerabilities affecting Microsoft 365 Copilot.
dCERT published Advisory 2026-1389 covering multiple vulnerabilities in Microsoft 365 Copilot Business Chat that could allow information disclosure.
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Microsoft disclosed a set of security flaws affecting cloud and AI services, including **Microsoft 365 Copilot**, **Microsoft Copilot**, **Microsoft 365 Copilot BizChat**, **Azure DevOps**, **Azure Cloud Shell**, **Azure Data Factory**, **Microsoft Bing**, and **Microsoft Bing Images**. The issues span **information disclosure**, **elevation of privilege**, **tampering**, and **remote code execution**, with published identifiers including `CVE-2026-24299`, `CVE-2026-26136`, `CVE-2026-26137`, `CVE-2026-23658`, `CVE-2026-32169`, `CVE-2026-23659`, `CVE-2026-26120`, and `CVE-2026-32191`. Germany's dCERT separately highlighted multiple vulnerabilities in **Microsoft 365 Copilot**, underscoring enterprise concern around AI-assisted productivity platforms. The most severe issue in the group is **`CVE-2026-32191`**, a **critical remote code execution** flaw in **Microsoft Bing Images**. Public reporting tied the bug to **OS command injection** caused by improper neutralization of special elements in a command, potentially allowing an unauthenticated attacker to execute code over a network. Additional Bing exposure was tracked as **`CVE-2026-26120`**, a tampering vulnerability, while the Copilot-related flaws included both **information disclosure** and **privilege escalation**, indicating risk to data confidentiality and tenant-level access boundaries across Microsoft's hosted services.
Jun 29, 2026
Microsoft confirmed a **Microsoft 365 Copilot Chat** bug that caused the Copilot *work tab* to incorrectly read and summarize users’ emails from **Sent Items** and **Drafts**, even when those messages had **confidential sensitivity labels** and organizations had **data loss prevention (DLP)** policies intended to prevent such processing. The issue was tracked as admin-visible incident `CW1226324`, first detected in late January, and was attributed to an unspecified **code error** that allowed labeled items to be picked up by Copilot despite protections being in place. Microsoft said it began rolling out a fix in early February and was still monitoring deployment while validating remediation with a subset of affected users; the company did not disclose how many customers were impacted or provide a firm timeline for full resolution. Separate reporting noted heightened institutional concern about built-in AI features handling sensitive correspondence (e.g., the European Parliament IT department blocking AI features on work devices), underscoring governance and data-handling risk when AI assistants can process content contrary to configured controls.
Jun 29, 2026
Researchers reported that vulnerabilities in Microsoft 365 Copilot and Consumer Copilot allowed attackers to turn prompt injection into data exfiltration, memory poisoning, and persistent compromise. Microsoft assigned `CVE-2026-24299` to the main issue set and rolled out fixes across late 2025 and early 2026, while a related Microsoft Excel flaw, `CVE-2026-26144`, showed how a conventional application bug could be chained with Copilot Agent mode to silently extract spreadsheet data. In the Copilot attacks, malicious content abused HTML preview rendering to leak sensitive information through external requests, first with CSS background images and later with `@font-face`, and researchers said users could be coerced into triggering the preview during normal interaction, creating a near zero-click exfiltration path. The research also showed that Copilot’s memory features could be poisoned to add or delete stored facts and implant persistent instructions that altered future sessions, enabling a backdoor dubbed **SpAIware** that continued leaking secrets over time. Similar issues were described in consumer Copilot, including durable-memory manipulation and browser-navigation exfiltration through Edge-integrated tooling. The findings underscore a broader security shift: AI assistants can collapse trust boundaries inside host applications, raising the impact of older flaws and forcing defenders to reassess assistant permissions, restrict outbound network access from AI-enabled apps, and separately monitor AI-initiated network activity.
Jun 29, 2026