PT-2026-39714 · Any1 · Neat Vnc

Published 2026-05-11 · Updated 2026-05-11 · CVE-2026-42859

NVD

CVSS v4.0

8.1

High

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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.

Fix

Buffer Overflow

Weakness Enumeration

CWE-120

Related Identifiers

CVE-2026-42859

Affected Products

Neat Vnc

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-42859 · Security Note
• https://github.com/any1/neatvnc/commit/1f6cd6b75cc167fed3a19a9d1552a1f662f6b337 · Note
• https://github.com/any1/neatvnc/security/advisories/GHSA-567c-gpv8-qh9h · Note