{"schemaVersion":3,"id":"CVE-2026-7831","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"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.","dates":{"published":"2026-07-01T03:33:25.314Z","modified":"2026-07-09T04:35:54.891Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7.6,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"NVD","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":7.6,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00738,"percentile":0.53759,"severity":"low","asOf":"2026-10-20T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-20T00:00:00.000Z","baselineScore":0.00738},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00738,"percentile":0.53759}],"last30":[{"date":"2026-09-20T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00738,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00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