Cross-Site Scripting (XSS) in SimpleChat (CVE-2026-105798)
Summary
Cross-site scripting in SimpleChat (CVE-2026-105798). Confidential information can be exposed externally. Exploitable via POST /api/group_documents/upload.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-105798 has been found in SimpleChat.
Attackers can target a specific entry point like POST /api/group_documents/upload over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.7/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "SimpleChat CVE-2026-105798" on the vendor's site.
CVE-2026-105798 (SimpleChat) — CWE-79 / CVSS v3 8.7
Attack vector: remote (network-reachable)
Attack surface: POST /api/group_documents/upload
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in SimpleChat. Attackers reach the vulnerable code path via POST /api/group_documents/upload.
Check the vendor advisory for the affected versions of SimpleChat. Attack surface: POST /api/group_documents/upload.
Severity: High (CVSS 8.7/10). Confidential information can be exposed externally.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /api/group_documents/upload requests with malformed payloads or SQL meta-characters. Run grep -r 'SimpleChat' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'SimpleChat' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
SimpleChatを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /api/group_documents/upload' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/group_documents/uploadへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Post-deployment verification verify
Replay attack against POST /api/group_documents/upload on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。