PT-2026-54484 · Uvnc · Ultravnc
Published
2026-07-01
·
Updated
2026-07-01
·
CVE-2026-7828
CVSS v3.1
5.3
Medium
| Vector | AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
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.
Fix
Integer Overflow
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Weakness Enumeration
Related Identifiers
Affected Products
Ultravnc