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

Quick assessment

Affected
any1 neatvnc
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Neat VNC是Andri Yngvason个人开发者的一个自由许可的 VNC 服务器库。 Neat VNC 0.9.6之前版本存在安全漏洞，该漏洞源于RSA-AES安全类型处理器中存在预认证栈缓冲区溢出，可能导致未认证远程攻击者通过发送特制RSA公钥造成拒绝服务。

AI Predicted 7.5 Difficulty: Easy EPSS 0.55% · P44

Affected Version Matrix 1

VendorProduct Version RangeStatus
any1 neatvnc < 0.9.6 affected
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I. Basic Information for CVE-2026-42859

Vulnerability Information
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Vulnerability Title
Neat VNC: Buffer overflow due to oversized RSA public keys
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
未进行输入大小检查的缓冲区拷贝(传统缓冲区溢出)
Source: CVE Program / CVE List V5
Vulnerability Title
Neat VNC 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Neat VNC是Andri Yngvason个人开发者的一个自由许可的 VNC 服务器库。 Neat VNC 0.9.6之前版本存在安全漏洞，该漏洞源于RSA-AES安全类型处理器中存在预认证栈缓冲区溢出，可能导致未认证远程攻击者通过发送特制RSA公钥造成拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
any1 neatvnc < 0.9.6 -

II. Public POCs for CVE-2026-42859

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III. Intelligence Information for CVE-2026-42859

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Patches & Fixes for CVE-2026-42859 (1)

Vendor Advisories for CVE-2026-42859 (1)

IV. Related Vulnerabilities

Same weakness: CWE-120

V. Comments for CVE-2026-42859

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