LibVNC LibVNCClient up to 0.9.15 heap-based overflow

Summaryinfo

A vulnerability has been found in LibVNC LibVNCClient up to 0.9.15 and classified as critical. This vulnerability affects unknown code. This manipulation causes heap-based overflow. This vulnerability appears as CVE-2026-50538. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in LibVNC LibVNCClient up to 0.9.15. It has been declared as critical. Affected by this vulnerability is an unknown part. The manipulation with an unknown input leads to a heap-based overflow vulnerability. The CWE definition for the vulnerability is CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

LibVNCClient is a library for easy implementation of a VNC client. In versions 0.9.12 through 0.9.15, a malicious (or man-in-the-middle) VNC server can force a connecting `libvncclient` to write attacker-controlled data past the end of its framebuffer. This is an out-of-bounds heap write with attacker-controlled length, contents, and offset. It needs no authentication (the attacker is the server), works in a default build with default settings, and fires from a single `FramebufferUpdate` the moment the victim connects. It crashes any client unconditionally (denial of service); we also demonstrated it overwriting an application callback pointer and redirecting execution to attacker-chosen code (code execution) under the default configuration. Commit 540332be3e0acc566fa64da6f1b4680c72c724dd patches the issue.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-50538 since 06/04/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available.

Applying the patch 540332be3e0acc566fa64da6f1b4680c72c724dd is able to eliminate this problem.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• LibVNC

Name

• LibVNCClient

Version

• 0.9.0
• 0.9.1
• 0.9.2
• 0.9.3
• 0.9.4
• 0.9.5
• 0.9.6
• 0.9.7
• 0.9.8
• 0.9.9
• 0.9.10
• 0.9.11
• 0.9.12
• 0.9.13
• 0.9.14
• 0.9.15

CPE 2.3info

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• 🔒
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CPE 2.2info

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