CVE-2026-7828 (GCVE-0-2026-7828)

Vulnerability from cvelistv5 – Published: 2026-07-01 03:33 – Updated: 2026-07-01 13:14
VLAI
Title
UltraVNC repeater integer overflow in win_log malloc leading to heap overflow
Summary
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.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-190 - Integer Overflow or Wraparound
Assigner
References
URL Tags
https://uvnc.com/ vendor-advisory
https://github.com/ultravnc/UltraVNC product
Impacted products
Vendor Product Version
uvnc UltraVNC Affected: 0 , ≤ 1.8.2.2 (custom)
Create a notification for this product.
Credits
Arjun Basnet, Securin (arjun.basnet@securin.io)
Show details on NVD website
To clipboard 

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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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