CVE-2026-7829: UltraVNC repeater through 1.8.2.2 contains a post-authentication out-of-bounds write in the allow/deny rule parser. In repeater/webgui/settings.c:225-272, after strncpy_s copies a

highCVSS 7.2CVE-2026-7829

UltraVNC repeater through 1.8.2.2 contains a post-authentication out-of-bounds write in the allow/deny rule parser. In repeater/webgui/settings.c:225-272, after strncpy_s copies a rule token into temp1[rule1] (25-byte destination) or temp2/temp3 (16-byte destination), the code unconditionally writes a NUL terminator at temp1[rule1][len] = 0 without clamping len to the destination size. When an authenticated administrator saves a rule with a token length equal to or greater than the destination size, the NUL byte is written one or more bytes past the end of the stack-allocated array, corrupting adjacent stack data. An attacker who has obtained admin credentials (including via CVE-2026-7839 default password) can trigger this to gain code execution on the repeater host.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 7.2
Published: 2026-07-01
Last updated: 2026-07-02
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-7829

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-78290.57% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 43% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-7829	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[NEW] [high] UltraVNC: Multiple vulnerabilitiescert-bund

Recent advisories for UltraVNC repeater

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

criticalCVE-2026-7840: UltraVNC repeater through 1.8.2.2 contains a global buffer overflow in its embedded HTTP admini…nvd · 2026-07-01
criticalCVE-2026-7839: UltraVNC repeater through 1.8.2.2 initializes the HTTP administration server with a hardcoded d…nvd · 2026-07-01
mediumCVE-2026-7828: UltraVNC repeater through 1.8.2.2 contains an integer overflow in the HTTP request logging path…nvd · 2026-07-01
lowCVE-2026-44042: UltraVNC repeater through 1.8.2.2 contains an off-by-one error in the Base64 decode helper use…nvd · 2026-07-01