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CVE-2026-32853— LibVNCServer UltraZip Encoding Heap Out-of-bounds Read

Quick assessment

Affected
LibVNC LibVNCServer
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.

LibVNCServer是LibVNC开源的一款支持在程序中实现VNC（虚拟网络计算）服务器或客户端功能的跨平台C语言库。 LibVNCServer 0.9.15及之前版本存在缓冲区错误漏洞，该漏洞源于UltraZip编码处理程序中存在堆越界读取，可能导致信息泄露或应用程序崩溃。

CVSS 6.9 · Medium EPSS 0.45% · P39

Possible ATT&CK Techniques 1 AI

T1005 · Data from Local System

Affected Version Matrix 2

VendorProduct Version RangeStatus
LibVNC LibVNCServer ≤ 0.9.15 affected
009008e2f4d5a54dd71f422070df3af7b3dbc931 unaffected
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I. Basic Information for CVE-2026-32853

Vulnerability Information
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Vulnerability Title
LibVNCServer UltraZip Encoding Heap Out-of-bounds Read
Source: CVE Program / CVE List V5
Vulnerability Description
LibVNCServer versions 0.9.15 and prior (fixed in commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5
Vulnerability Title
LibVNCServer 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
LibVNCServer是LibVNC开源的一款支持在程序中实现VNC（虚拟网络计算）服务器或客户端功能的跨平台C语言库。 LibVNCServer 0.9.15及之前版本存在缓冲区错误漏洞，该漏洞源于UltraZip编码处理程序中存在堆越界读取，可能导致信息泄露或应用程序崩溃。
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
LibVNC LibVNCServer 0 ~ 0.9.15 -

II. Public POCs for CVE-2026-32853

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III. Intelligence Information for CVE-2026-32853

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Patches & Fixes for CVE-2026-32853 (1)

Vendor Advisories for CVE-2026-32853 (2)

IV. Related Vulnerabilities

Same product: LibVNCServer
Same vendor: LibVNC
Same weakness: CWE-125