---
id: CVE-2026-105798
title: >-
  SimpleChat is a secure AI conversation application with personal and group
  workspaces for document-grounded interactions
summary: >-
  SimpleChat is a secure AI conversation application with personal and group
  workspaces for document-grounded interactions. Prior to 0.261.029, POST
  /api/group_documents/upload stores an attacker-controlled group document
  filename that gro…
severity: high
cvss: 8.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N'
cwe:
  - CWE-79
vendor: microsoft
product: simplechat
affected:
  - simplechat < 0.261.029
published: '2026-10-06'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T15:25:00.650'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-105798'
references:
  - url: >-
      https://github.com/microsoft/simplechat/commit/537a259eb048b8f6d1c94193fa0c9683ab0bace9
    label: security-advisories@github.com
  - url: >-
      https://github.com/microsoft/simplechat/security/advisories/GHSA-qwcw-r653-j8c6
    label: security-advisories@github.com
  - url: >-
      https://github.com/microsoft/simplechat/security/advisories/GHSA-qwcw-r653-j8c6
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-06T14:44:18.403661Z'
ingestedAt: '2026-10-06T15:01:49.297Z'
---

## Overview

SimpleChat is a secure AI conversation application with personal and group workspaces for document-grounded interactions. Prior to 0.261.029, POST /api/group_documents/upload stores an attacker-controlled group document filename that group_workspaces.html later interpolates into inline Share event handlers. The escapeGroupHtml function leaves apostrophes unchanged, while escapeHtml produces an HTML entity that the browser decodes before JavaScript evaluation, so either path permits the filename to terminate the handler string. An authenticated group Owner, Admin, or DocumentManager can persist script that executes in the SimpleChat origin when another group member clicks Share, allowing access to victim-visible data and actions with the victim session. This issue is fixed in version 0.261.029.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.