CVE-2026-7829 | UltraVNC repeater authenticated out-of-bounds write in rule parser via oversized token

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.

Published: 2026-07-01 Last update: 2026-07-09 Assigner: 33c584b5-0579-4c06-b2a0-8d8329fcab9c Source: 33c584b5-0579-4c06-b2a0-8d8329fcab9c
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-7829 is rated Moderate Risk (44/100): CVSS High severity, with low exploitation likelihood (EPSS 0.57%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-7829

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-07-09 0.50% 0.57% +0.07%
2 2026-07-01 — 0.50% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-7829

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.2 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.2 5.9 33c584b5-0579-4c06-b2a0-8d8329fcab9c

Weakness enumeration for CVE-2026-7829

GitHub Security Advisory for CVE-2026-7829

GHSA-fxj2-5q9g-wmp9 · Severity: high — UltraVNC repeater through 1.8.2.2 contains a post-authentication out-of-bounds write in the allow...

Affected software / configurations for CVE-2026-7829

Vendor Product Version Raw CPE
uvnc ultravnc <= 1.8.2.2 cpe:2.3:a:uvnc:ultravnc:*:*:*:*:*:*:*:*

References for CVE-2026-7829

cvelogic Threat Intelligence