Vulnerability Details CVE-2026-7828
UltraVNC repeater through 1.8.2.2 contains an integer overflow in the HTTP request logging path. In repeater/webgui/settings.c:336, the win_log() function allocates list nodes via malloc(sizeof(struct LIST) + strlen(line)), where line is derived from HTTP request URIs. If strlen(line) is sufficiently large, the addition overflows to a value smaller than sizeof(struct LIST), causing a heap allocation smaller than required. The subsequent strcpy of the full string into the undersized allocation produces a heap buffer overflow. In the current implementation this overflow is bounded by the HTTP receive buffer size (WI_RXBUFSIZE = 153600 bytes, well below SIZE_MAX on 32-bit builds), limiting practical exploitability to a partial heap write. A remote unauthenticated attacker can trigger the theoretical overflow path by sending a maximally-sized URI in an HTTP request to the repeater HTTP port.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.008
EPSS Ranking 53.4%
CVSS Severity
CVSS v3 Score 5.3
Products affected by CVE-2026-7828
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cpe:2.3:a:uvnc:ultravnc:1.0.9.6.2
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cpe:2.3:a:uvnc:ultravnc:1.1.8.9
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cpe:2.3:a:uvnc:ultravnc:1.1.9.3
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cpe:2.3:a:uvnc:ultravnc:1.1.9.6
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cpe:2.3:a:uvnc:ultravnc:1.2.0.5
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cpe:2.3:a:uvnc:ultravnc:1.2.0.9
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cpe:2.3:a:uvnc:ultravnc:1.2.1.0
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cpe:2.3:a:uvnc:ultravnc:1.2.1.2
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cpe:2.3:a:uvnc:ultravnc:1.2.1.6
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cpe:2.3:a:uvnc:ultravnc:1.2.1.7
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cpe:2.3:a:uvnc:ultravnc:1.2.2.2
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cpe:2.3:a:uvnc:ultravnc:1.2.2.3
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cpe:2.3:a:uvnc:ultravnc:1.2.2.4
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cpe:2.3:a:uvnc:ultravnc:1.2.4.0
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cpe:2.3:a:uvnc:ultravnc:1.3.2
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cpe:2.3:a:uvnc:ultravnc:1.3.4
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cpe:2.3:a:uvnc:ultravnc:1.3.4.1
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cpe:2.3:a:uvnc:ultravnc:1.3.4.2
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cpe:2.3:a:uvnc:ultravnc:1.3.6.0
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cpe:2.3:a:uvnc:ultravnc:1.3.8.0
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cpe:2.3:a:uvnc:ultravnc:1.3.8.1
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cpe:2.3:a:uvnc:ultravnc:1.4.0.5
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cpe:2.3:a:uvnc:ultravnc:1.4.0.6
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cpe:2.3:a:uvnc:ultravnc:1.4.0.9
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cpe:2.3:a:uvnc:ultravnc:1.4.2.0
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cpe:2.3:a:uvnc:ultravnc:1.4.3.0
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cpe:2.3:a:uvnc:ultravnc:1.4.3.1
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cpe:2.3:a:uvnc:ultravnc:1.4.3.5
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cpe:2.3:a:uvnc:ultravnc:1.4.3.6
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cpe:2.3:a:uvnc:ultravnc:1.5.0.0
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cpe:2.3:a:uvnc:ultravnc:1.6.0.0
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cpe:2.3:a:uvnc:ultravnc:1.6.1.0
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cpe:2.3:a:uvnc:ultravnc:1.6.4.0
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cpe:2.3:a:uvnc:ultravnc:1.8.2.2