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TI-2026-68451 Aliases CVE-2026-105798

Stored XSS in SimpleChat group document filenames

Priority HIGH 73CWE-79Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Required
Attack complexity
Low
Impact type
Cross-site scripting
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.

Summary

SimpleChat versions before 0.261.029 are affected. The group document upload stores an attacker-controlled filename that the group workspace page places into inline Share event handlers, where apostrophes are not escaped. An authenticated group Owner, Admin, or DocumentManager can store script that runs in the SimpleChat origin when another group member clicks Share, gaining access to that member's data and actions. The weakness is CWE-79.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00465 40th percentileScored 2026-11-07
Fix Fixed simplechat (microsoft): 0.261.029

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Microsoftsimplechatbefore 0.261.0290.261.029Patch availableCNA
  • simplechat VendorMicrosoft Affected before 0.261.029 Fixed in 0.261.029 Patch available CNA

Remediation

Upgrade SimpleChat to version 0.261.029, which fixes this issue.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA simplechat (microsoft) Fixed in 0.261.029

Timeline

  1. 2026-10-06 Threatist record created from CVE-2026-105798

References

Other 2

  • TI-2026-42212 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-37256 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-26194 Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-16982 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-36863 Windows Server Update Service (WSUS) Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-33671 Microsoft SharePoint Server Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
See all 18045 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences