CVE-2026-105798: high-severity vulnerability in microsoft simplechat
SimpleChat: Stored XSS via group document filename in inline onclick handler
Published
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.7epss 0.5%
exploitation probability
0.5%top 62% of all CVEs
observed exploitation
nono source reports it
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.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Affected products
microsoft · simplechatRelated CVEs — microsoft simplechat
In the same product, most dangerous first.
CVE-2026-57206HIGHSimpleChat plugin validation endpoints missing authentication and authorizationEPSS 1.0%CVE-2026-57205MEDIUMSimpleChat: Authenticated users can access other users' profile metadata through user IDOR endpointsEPSS 0.9%CVE-2026-105797HIGHSimpleChat: Command injection via authorization-gate ordering flaw (arbitrary process spawn through MCP stdio transport)EPSS 0.6%