Cross-Site Scripting in SimpleChat Affecting Microsoft
CVE-2026-105798

8.7HIGH

Key Information:

Vendor

Microsoft
Status
Simplechat
Vendor
CVE Published:
6 October 2026

What is CVE-2026-105798?

In SimpleChat, prior to version 0.261.029, a vulnerability allows an attacker to upload a malicious group document with a filename that can be executed in the context of the application. This arises from mishandled user input in event handlers, leading to potential script execution when other users click on the Share functionality. Authenticated users with roles like Owner, Admin, or DocumentManager can exploit this issue, gaining unauthorized access to victim-session data and actions. The vulnerability has been addressed in version 0.261.029.

Affected Version(s)

simplechat < 0.261.029

References

https://github.com/microsoft/simplechat/security/advisori...
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https://github.com/microsoft/simplechat/commit/537a259eb0...
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CVSS V3.1

Score:
8.7
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
Required
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.