CVE-2026-7829
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network with an admin-level account. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 0.9% chance of exploitation in the next 30 days (EPSS).
- Fix
- No patch or advisory is linked yet. Look at mitigations or restrict exposure.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.9% in the next 30 days (EPSS).
- Severity: 7.2 HIGH (CVSS).
- Fix: none linked yet, which raises it.
Details
- Published
- Last modified
- Exploit probability
- 0.9% · EPSS, next 30 days
- Weakness
- CWE-787 · Out-of-bounds write
- Record status
- Modified
Affected
- Uvnc Ultravnc ≤ 1.8.2.2
Attack profile CVSS 3.1 · 7.2
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-7829.md and follow it. Check whether this project is affected by CVE-2026-7829. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
