CVE-2026-77805
In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by the application is insufficient. Before executing a helper tool, the application only verifies that the file carries a valid Authenticode signature whose certificate subject name matches a broad allow list of publisher name fragments, rather than verifying that the file is the specific executable shipped with that version of the product.
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A local threat actor with low privileges who replaces one of these helper executables with any other validly signed binary from an allow-listed publisher can cause the substituted binary to be executed by the application, including with Administrator privileges for the tools that request elevation, resulting in privilege escalation and execution of unintended code. Successful exploitation requires the user to launch the affected external tool and to approve the elevation prompt without noticing that it refers to a different executable.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
- Puntuación base: 7.9
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.06%
- Percentil entre todas las CVEs puntuadas: 0
- Fecha de la puntuación: 6/10/2026
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
T1203Exploitation for Client Executionexecution85 % - Impacto principal
T1068Exploitation for Privilege Escalationprivilege escalation90 % - Impacto secundario
T1059Command and Scripting Interpreterexecution80 %
AV:L + UI:R indica ejecución en cliente; requiere que el usuario lance la herramienta y apruebe el prompt. El atacante reemplaza un ejecutable firmado para escalar privilegios (PR:L→Admin) y ejecutar código arbitrario.
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-347
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-77805",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-77805",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-10-05T15:25:58.985097Z"
}
}
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"cvssMetricV31": [
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"version": "3.1",
"baseScore": 7.9,
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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/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": 1.5
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"affected": [
{
"source": "security@progress.com",
"affectedData": [
{
"vendor": "Progress Software",
"product": "Progress® Telerik® Fiddler® Classic",
"versions": [
{
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"version": "1.0.0",
"lessThan": "6.0.20262.10021",
"versionType": "custom"
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],
"platforms": [
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"published": "2026-10-05T13:16:54.740",
"references": [
{
"url": "https://docs.telerik.com/fiddler/knowledge-base/kb-security-weak-executable-signature-verification-cve-2026-77805",
"source": "security@progress.com"
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"vulnStatus": "Awaiting Analysis",
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"description": [
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"descriptions": [
{
"lang": "en",
"value": "In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by the application is insufficient. Before executing a helper tool, the application only verifies that the file carries a valid Authenticode signature whose certificate subject name matches a broad allow list of publisher name fragments, rather than verifying that the file is the specific executable shipped with that version of the product. A local threat actor with low privileges who replaces one of these helper executables with any other validly signed binary from an allow-listed publisher can cause the substituted binary to be executed by the application, including with Administrator privileges for the tools that request elevation, resulting in privilege escalation and execution of unintended code. Successful exploitation requires the user to launch the affected external tool and to approve the elevation prompt without noticing that it refers to a different executable."
}
],
"lastModified": "2026-10-06T15:09:20.387",
"sourceIdentifier": "security@progress.com"
}