PT-2026-39714 · Neat Vnc · Neat Vnc

Any1 · Published 2026-05-11 · Updated 2026-05-11 · CVE-2026-42859

Positive Technologies (AI Summary)

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

Name of the Vulnerable Software and Affected Versions Neat VNC versions prior to 0.9.6

Description A pre-authentication stack buffer overflow exists in the RSA-AES security type handler. An unauthenticated remote attacker can send a crafted security type 5 (RSA-AES) or security type 129 (RSA-AES-256) handshake containing an oversized client RSA public key. This causes the rsa aes send challenge() function in src/auth/rsa-aes.c to overflow a 1024-byte on-stack buffer during the encryption of the server challenge, leading to a denial of service via a server crash.

Recommendations Update to version 0.9.6.

Fix

Buffer Overflow

Weakness Enumeration

CWE-120

Related Identifiers

CVE-2026-42859

Affected Products

Neat Vnc

References · 9

• https://security-tracker.debian.org/tracker/CVE-2026-42859 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-42859 · Security Note
• https://ubuntu.com/security/CVE-2026-42859 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-42859 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-42859 · Vendor Advisory
• https://cve.org/CVERecord?id=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
• https://twitter.com/CVEnew/status/2053932398237335872 · Twitter Post