I would like to thank Microsoft product teams and Microsoft Security Response Center (MSRC) for collaborating with me on this technical analysis and mitigation of the disclosed vulnerabilities. The editorial opinions reflected below are solely the author’s and do not necessarily reflect those of the organizations I collaborated with. Summary The findings described in this post are part of a coordinated disclosure with MSRC and Microsoft product teams. Microsoft was provided with reproduction steps, videos, environmental assumptions, and the exact proof-of-concept (PoC) prompts used during testing. They were also informed of a 90-day coordination period before disclosure. This was extended two times, resulting a 144-day coordination period. In parts 1 and 2 in this series, I have shown how external inputs could influence Copilot responses and, in some cases, potentially lead to confidentiality impacts through Cross-Domain Prompt Injection Attacks (XPIAs) .…