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.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://github.com/ultravnc/UltraVNC	Product
https://uvnc.com/	Product Release Notes
https://www.securin.io/zero-days/cve-2026-7828-integer-overflow-win-log-malloc-ultravnc-repeater

Configurations

Configuration 1 (hide)

cpe:2.3:a:uvnc:ultravnc:*:*:*:*:*:*:*:*

History

09 Jul 2026, 06:16

Type	Values Removed	Values Added
References		() https://www.securin.io/zero-days/cve-2026-7828-integer-overflow-win-log-malloc-ultravnc-repeater -

02 Jul 2026, 15:07

Type	Values Removed	Values Added
CPE		cpe:2.3:a:uvnc:ultravnc::::::::
First Time		Uvnc Uvnc ultravnc
References	~~() https://github.com/ultravnc/UltraVNC -~~	() https://github.com/ultravnc/UltraVNC - Product
References	~~() https://uvnc.com/ -~~	() https://uvnc.com/ - Product, Release Notes

01 Jul 2026, 05:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-01 05:16

Updated : 2026-07-09 06:16

NVD link : CVE-2026-7828

Mitre link : CVE-2026-7828

CVE.ORG link : CVE-2026-7828

JSON object : View

Products Affected

uvnc

ultravnc

CWE

CWE-190

Integer Overflow or Wraparound

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