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.

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Fixes

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History

Mon, 11 May 2026 19:45:00 +0000

Type Values Removed Values Added
First Time appeared Any1
Any1 neatvnc
Vendors & Products Any1
Any1 neatvnc

Mon, 11 May 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Mon, 11 May 2026 18:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Neat VNC: Buffer overflow due to oversized RSA public keys
Weaknesses CWE-120
References
Metrics cvssV4_0

{'score': 8.1, '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'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-11T18:22:03.144Z

Reserved: 2026-04-30T16:44:48.379Z

Link: CVE-2026-42859

cve-icon Vulnrichment

Updated: 2026-05-11T18:21:49.508Z

cve-icon NVD

Status : Received

Published: 2026-05-11T18:16:36.400

Modified: 2026-05-11T18:16:36.400

Link: CVE-2026-42859

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-11T19:30:06Z

Weaknesses