CVE-2026-50538: libvncclient Tight decoder has an attacker-controlled heap out-of-bounds write
LibVNC · libvncserver
Affected: libvncserver · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 35% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- LibVNC · libvncserver>= 0.9.12, <= 0.9.15
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- LibVNC
- Published
- August 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-50538 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.