CVE-2026-42859 HIGH

CVE-2026-42859: Neat VNC: Buffer overflow due to oversized RSA public keys

Vendor Any1
Product neatvnc
Weakness CWE-120
Published May 11, 2026
Last update May 11, 2026

CVSS base score

8.1/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U

What the vulnerability does

01Description

Neat VNC is a VNC server library. Prior to 0.9.6, a pre-authentication stack buffer overflow exists in neatvnc in the RSA-AES security type handler. An unauthenticated remote attacker who can reach the VNC listening socket can send a crafted security type 5 (RSA-AES) or security type 129 (RSA-AES-256) handshake with an oversized client RSA public key, causing rsa_aes_send_challenge in src/auth/rsa-aes.c to overflow a 1024-byte on-stack buffer when encrypting the server challenge. This results in at least a denial of service via server crash. This vulnerability is fixed in 0.9.6.

Key dates

02Disclosure timeline

May 11, 2026 CVE published
May 11, 2026 Record updated