CVE-2026-105798
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.
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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
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
- Puntuación base: 8.7
Probabilidad de explotación (EPSS)
FIRST aún no ha puntuado esta CVE (habitual en CVEs muy recientes o rechazadas).
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1189Drive-by Compromiseinitial access90 % - Impacto principal
T1059.007JavaScriptexecution85 % - Impacto secundario
T1005Data from Local Systemcollection80 %
XSS persistente en nombres de archivo (CWE-79) ejecutado al hacer clic en Share. Requiere autenticación de grupo pero afecta a otros usuarios. Vector CVSS muestra UI:R (interacción del usuario), confirmando T1189. JavaScript en navegador (T1059.007) y acceso a datos visibles en sesión (T1005).
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-79
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-105798",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-105798",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-10-06T14:44:18.403661Z"
}
}
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"cvssMetricV31": [
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"type": "Secondary",
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"version": "3.1",
"baseScore": 8.7,
"attackVector": "NETWORK",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N",
"integrityImpact": "HIGH",
"userInteraction": "REQUIRED",
"attackComplexity": "LOW",
"availabilityImpact": "NONE",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.8,
"exploitabilityScore": 2.3
}
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"affected": [
{
"source": "security-advisories@github.com",
"affectedData": [
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"vendor": "microsoft",
"product": "simplechat",
"versions": [
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"status": "affected",
"version": "< 0.261.029"
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"published": "2026-10-06T15:17:16.880",
"references": [
{
"url": "https://github.com/microsoft/simplechat/commit/537a259eb048b8f6d1c94193fa0c9683ab0bace9",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/microsoft/simplechat/security/advisories/GHSA-qwcw-r653-j8c6",
"source": "security-advisories@github.com"
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{
"url": "https://github.com/microsoft/simplechat/security/advisories/GHSA-qwcw-r653-j8c6",
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
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"vulnStatus": "Deferred",
"weaknesses": [
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"source": "security-advisories@github.com",
"description": [
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"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"lastModified": "2026-10-06T15:25:00.650",
"sourceIdentifier": "security-advisories@github.com"
}