Stack-based buffer overflow in neatvnc - CVE-2026-42859
Published: April 25, 2026
Vulnerability identifier: #VU127902
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-42859
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to stack-based buffer overflow in rsa_aes_send_challenge in src/auth/rsa-aes.c when handling an RSA-AES security type handshake with an oversized client RSA public key. A remote attacker can send a crafted security type 5 or 129 handshake to cause a denial of service.
The issue is pre-authentication and requires network reachability to the VNC listening socket.
Affected software
neatvnc
How to mitigate CVE-2026-42859
Install security update from vendor's website.
neatvnc - update to 0.9.6