CVE-2026-7829

{"id": "CVE-2026-7829", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-7829", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-07-01T13:13:45.463427Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.2, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "HIGH", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 1.2}]}, "affected": [{"source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "affectedData": [{"vendor": "uvnc", "modules": ["repeater"], "product": "UltraVNC", "versions": [{"status": "affected", "version": "0", "versionType": "custom", "lessThanOrEqual": "1.8.2.2"}], "defaultStatus": "unaffected"}]}], "published": "2026-07-01T05:16:24.087", "references": [{"url": "https://github.com/ultravnc/UltraVNC", "tags": ["Product"], "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c"}, {"url": "https://uvnc.com/", "tags": ["Product", "Release Notes"], "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c"}, {"url": "https://www.securin.io/zero-days/cve-2026-7829-post-auth-oob-nul-write-repeater-rule-parser-ultravnc", "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Secondary", "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "description": [{"lang": "en", "value": "CWE-787"}]}], "descriptions": [{"lang": "en", "value": "UltraVNC repeater through 1.8.2.2 contains a post-authentication out-of-bounds write in the allow/deny rule parser. In repeater/webgui/settings.c:225-272, after strncpy_s copies a rule token into temp1[rule1] (25-byte destination) or temp2/temp3 (16-byte destination), the code unconditionally writes a NUL terminator at temp1[rule1][len] = 0 without clamping len to the destination size. When an authenticated administrator saves a rule with a token length equal to or greater than the destination size, the NUL byte is written one or more bytes past the end of the stack-allocated array, corrupting adjacent stack data. An attacker who has obtained admin credentials (including via CVE-2026-7839 default password) can trigger this to gain code execution on the repeater host."}, {"lang": "es", "value": "El repetidor UltraVNC hasta la versi\u00f3n 1.8.2.2 contiene una escritura fuera de l\u00edmites post-autenticaci\u00f3n en el analizador de reglas de permitir/denegar. En repeater/webgui/settings.c:225-272, despu\u00e9s de que strncpy_s copia un token de regla en temp1[rule1] (destino de 25 bytes) o temp2/temp3 (destino de 16 bytes), el c\u00f3digo escribe incondicionalmente un terminador NUL en temp1[rule1][len] = 0 sin ajustar \u2019len\u2019 al tama\u00f1o del destino. Cuando un administrador autenticado guarda una regla con una longitud de token igual o mayor que el tama\u00f1o del destino, el byte NUL se escribe uno o m\u00e1s bytes m\u00e1s all\u00e1 del final del array asignado en la pila, corrompiendo datos adyacentes de la pila. Un atacante que ha obtenido credenciales de administrador (incluyendo a trav\u00e9s de la contrase\u00f1a predeterminada CVE-2026-7839) puede activar esto para obtener ejecuci\u00f3n de c\u00f3digo en el host del repetidor."}], "lastModified": "2026-10-25T17:10:00.197", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:uvnc:ultravnc:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "593F7EC1-0922-4652-817A-7D57A0F1210D", "versionEndIncluding": "1.8.2.2"}], "operator": "OR"}]}], "sourceIdentifier": "33c584b5-0579-4c06-b2a0-8d8329fcab9c"}