CVE-2026-7828
UltraVNC repeater through 1.8.2.2 contains an integer overflow in the HTTP request logging path.
Does this matter?
Lower severity and a low EPSS score (1.35%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- EPSS
- 1.35% probability · 70th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-190
- Affected
- uvnc/ultravnc
- Source
- 33c584b5-0579-4c06-b2a0-8d8329fcab9c
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.