CVE-2026-7828 uvnc CVE debrief

Who should care

Users of UltraVNC repeater version 1.8.2.2 or earlier should apply patches or mitigations. This includes operators, administrators, and security teams responsible for maintaining and securing systems that utilize UltraVNC repeater. Vulnerability management and security teams should review the official advisory and CVE record to validate affected scope and vendor guidance.

Technical 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.

Defensive priority

Apply patches or updates to UltraVNC repeater to prevent potential heap buffer overflows. Restrict access to the repeater HTTP port and monitor for suspicious HTTP requests.

Recommended defensive actions

• Apply patches or updates to UltraVNC repeater
• Restrict access to the repeater HTTP port
• Monitor for suspicious HTTP requests
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. Additional information from source references may be necessary for thorough understanding. Evidence limits suggest that further verification is required to confirm affected scope and severity. Defenders should review the official advisory and CVE record to validate affected systems and vendor guidance.

Official resources