{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-7831", "assignerOrgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "state": "PUBLISHED", "assignerShortName": "securin", "dateReserved": "2026-05-05T04:03:22.622Z", "datePublished": "2026-07-01T03:33:25.314Z", "dateUpdated": "2026-07-01T13:12:46.218Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "shortName": "securin", "dateUpdated": "2026-07-01T03:33:25.314Z"}, "title": "UltraVNC viewer off-by-one stack overflow in ServerInit desktop name parsing", "descriptions": [{"lang": "en", "value": "UltraVNC viewer through 1.8.2.2 contains an off-by-one stack buffer overflow in the RFB ServerInit message handler. In vncviewer/ClientConnection.cpp, when the server-supplied nameLength equals exactly 2024 the code declares a 2024-byte stack buffer _dn[2024] and calls ReadString(_dn, 2024). ReadString writes the NUL terminator at buf[length], i.e., _dn[2024], one byte past the end of the stack buffer. A malicious VNC server can trigger this condition by advertising a desktop name of length 2024 in its ServerInit message. On release builds without stack canaries the single-byte NUL overwrite adjacent stack data. On builds with /GS stack protection the canary is corrupted and the process terminates, resulting in denial of service. User interaction (connecting the viewer to the malicious server) is required."}], "affected": [{"vendor": "uvnc", "product": "UltraVNC", "versions": [{"version": "0", "lessThanOrEqual": "1.8.2.2", "status": "affected", "versionType": "custom"}], "defaultStatus": "unaffected", "modules": ["vncviewer"]}], "problemTypes": [{"descriptions": [{"type": "CWE", "cweId": "CWE-193", "lang": "en", "description": "Off-by-one Error"}]}, {"descriptions": [{"type": "CWE", "cweId": "CWE-787", "lang": "en", "description": "Out-of-bounds Write"}]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH"}}], "references": [{"url": "https://uvnc.com/", "name": "UltraVNC project page", "tags": ["vendor-advisory"]}, {"url": "https://github.com/ultravnc/UltraVNC", "name": "UltraVNC source repository", "tags": ["product"]}], "timeline": [{"time": "2026-06-02T00:00:00.000Z", "lang": "en", "value": "Vulnerability discovered during security audit"}, {"time": "2026-06-17T00:00:00.000Z", "lang": "en", "value": "Reported to vendor (coordinated disclosure)"}, {"time": "2026-09-15T00:00:00.000Z", "lang": "en", "value": "Planned public disclosure (90-day window)"}], "credits": [{"lang": "en", "value": "Arjun Basnet, Securin (arjun.basnet@securin.io)", "type": "finder"}], "source": {"discovery": "EXTERNAL", "advisory": "Securin Security Advisory \u2014 FINDING-011"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-07-01T13:12:22.055256Z", "id": "CVE-2026-7831", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-01T13:12:46.218Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-7831", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-07-01T13:12:22.055256Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-01T13:12:42.509Z"}}], "cna": {"title": "UltraVNC viewer off-by-one stack overflow in ServerInit desktop name parsing", "source": {"advisory": "Securin Security Advisory \u2014 FINDING-011", "discovery": "EXTERNAL"}, "credits": [{"lang": "en", "type": "finder", "value": "Arjun Basnet, Securin (arjun.basnet@securin.io)"}], "metrics": [{"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H", "integrityImpact": "LOW", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"vendor": "uvnc", "modules": ["vncviewer"], "product": "UltraVNC", "versions": [{"status": "affected", "version": "0", "versionType": "custom", "lessThanOrEqual": "1.8.2.2"}], "defaultStatus": "unaffected"}], "timeline": [{"lang": "en", "time": "2026-06-02T00:00:00.000Z", "value": "Vulnerability discovered during security audit"}, {"lang": "en", "time": "2026-06-17T00:00:00.000Z", "value": "Reported to vendor (coordinated disclosure)"}, {"lang": "en", "time": "2026-09-15T00:00:00.000Z", "value": "Planned public disclosure (90-day window)"}], "references": [{"url": "https://uvnc.com/", "name": "UltraVNC project page", "tags": ["vendor-advisory"]}, {"url": "https://github.com/ultravnc/UltraVNC", "name": "UltraVNC source repository", "tags": ["product"]}], "descriptions": [{"lang": "en", "value": "UltraVNC viewer through 1.8.2.2 contains an off-by-one stack buffer overflow in the RFB ServerInit message handler. In vncviewer/ClientConnection.cpp, when the server-supplied nameLength equals exactly 2024 the code declares a 2024-byte stack buffer _dn[2024] and calls ReadString(_dn, 2024). ReadString writes the NUL terminator at buf[length], i.e., _dn[2024], one byte past the end of the stack buffer. A malicious VNC server can trigger this condition by advertising a desktop name of length 2024 in its ServerInit message. On release builds without stack canaries the single-byte NUL overwrite adjacent stack data. On builds with /GS stack protection the canary is corrupted and the process terminates, resulting in denial of service. User interaction (connecting the viewer to the malicious server) is required."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-193", "description": "Off-by-one Error"}]}, {"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-787", "description": "Out-of-bounds Write"}]}], "providerMetadata": {"orgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "shortName": "securin", "dateUpdated": "2026-07-01T03:33:25.314Z"}}}, "cveMetadata": {"cveId": "CVE-2026-7831", "state": "PUBLISHED", "dateUpdated": "2026-07-01T13:12:46.218Z", "dateReserved": "2026-05-05T04:03:22.622Z", "assignerOrgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "datePublished": "2026-07-01T03:33:25.314Z", "assignerShortName": "securin"}, "dataVersion": "5.2"}

{}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,1.8.2.2]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "UltraVNC", "source": "cna", "vendor": "uvnc"}, "product": "ultravnc", "vendor": "uvnc"}], "created": "2026-07-01T09:00:14.844033+00:00", "updated": "2026-07-01T15:15:04.136326+00:00", "vendors": ["uvnc", "uvnc$PRODUCT$ultravnc"]}