CVE-2026-44040

UltraVNC through 1.8.2.2 uses a cryptographically weak pseudo-random number generator to produce VNC authentication challenge bytes. In rfb/vncauth.c:119-129, the vncRandomBytes function seeds libc rand with time0 + getpid + rand and generates a 16-byte challenge. The combined seed space is...

CVE-2026-7838

UltraVNC viewer up to 1.8.2.2 is affected by an integer overflow leading to a heap buffer overflow in the RFB failure-response parsing path. In vncviewer/ClientConnection.cpp, the 4-byte reasonLen field is used as reasonLen+1 in CheckBufferSize(); with unsigned 32-bit operands, reasonLen 0xFFFFFF...

CVE-2026-44040

UltraVNC

PT-2026-54488

Name of the Vulnerable Software and Affected Versions UltraVNC viewer versions prior to 1.8.2.3 Description An integer overflow exists in the RFB protocol failure-response parsing path within the vncviewer/ClientConnection.cpp file. The issue occurs when the 4-byte network-supplied reasonLen fiel...

PT-2026-54477

Name of the Vulnerable Software and Affected Versions UltraVNC versions prior to 1.8.2.3 Description The software uses a cryptographically weak pseudo-random number generator to produce VNC authentication challenge bytes. Specifically, the vncRandomBytes function seeds libc rand using a combinati...

PYSEC-2026-365 TigerVNC accessible via the network and not just via a UNIX socket as intended

Summary jupyter-remote-desktop-proxy was meant to rely on UNIX sockets readable only by the current user since version 3.0.0, but when used with TigerVNC, the VNC server started by jupyter-remote-desktop-proxy were still accessible via the network. This vulnerability does not affect users having...

RockyLinux 8 : tigervnc (RLSA-2026:28923)

The remote RockyLinux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:28923 advisory. xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libXfont2 name length mismatch...

Astra Linux – Vulnerability in libvncserver

A divide by zero issue was detected in libvncserver-0.9.12. A malicious client could exploit this flaw to send a specially crafted message. When this message is processed by the VNC server, it will cause a floating-point exception, resulting in a denial of service...

Astra Linux – Vulnerability in Qemu

A flaw was discovered in the QEMU-built-in VNC server during the processing of ClientCutText messages. A incorrect exit condition may lead to an infinite loop when inflating a zlib buffer controlled by an attacker in the inflatebuffer function. This could allow a remotely authenticated client, wh...

Astra Linux – Vulnerability in Qemu

A flaw was discovered in the QEMU’s built-in VNC server during the processing of ClientCutText messages. The qemuclipboardrequest function can be accessed before vncservercuttextcaps is called, which gives a malicious authenticated VNC client the opportunity to initialize the clipboard peer. This...

Astra Linux – Vulnerability in Qemu

A flaw was discovered in the QEMU-built-in VNC server. When a client connects to the VNC server, QEMU checks whether the current number of connections exceeds a certain threshold. If it does, QEMU terminates the previous connection. However, if the previous connection is still in the handshake...

EUVD-2026-36803

A heap buffer overflow vulnerability was found in GStreamer's librfb RFB/VNC client. The rectangle bounds check incorrectly validates area rather than individual dimensions, allowing a malicious VNC server to send a rectangle that extends beyond the framebuffer. A remote attacker could set up a...

CVE-2026-52720 Gstreamer1-plugins-bad-free: gstreamer: heap buffer overflow via crafted vnc server rectangle in librfb

A heap buffer overflow vulnerability was found in GStreamer's librfb RFB/VNC client. The rectangle bounds check incorrectly validates area rather than individual dimensions, allowing a malicious VNC server to send a rectangle that extends beyond the framebuffer. A remote attacker could set up a...

PT-2026-49336

Name of the Vulnerable Software and Affected Versions GStreamer affected versions not specified Description A heap buffer overflow exists in the librfb RFB/VNC client component of GStreamer. The issue occurs because the rectangle bounds check validates the total area instead of individual...

TigerVNC: x0vncserver: TigerVNC x0vncserver: Information disclosure, data manipulation, and denial of service via incorrect permissions

A flaw was found in TigerVNC's x0vncserver component. Due to incorrect permissions in the Image.cxx file, other users on the system can observe or manipulate the screen contents of a running session. This vulnerability could also lead to an application crash, resulting in a Denial of Service DoS...

RHEL 9 : qemu-kvm (RHSA-2026:22147)

The remote Redhat Enterprise Linux 9 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2026:22147 advisory. Kernel-based Virtual Machine KVM is a full virtualization solution for Linux on a variety of architectures. The qemu-kvm packages provide the...

OESA-2026-2565 libvncserver security update

libvncserver is a set of programs using the RFB Remote Frame Buffer protocol. They are designed to "export" a frame buffer via net: you set up a server and can connect to it via VNC viewers. If the server supports WebSockets which LibVNCServer does, you can also connect using an in-browser VNC...

Low: Red Hat Security Advisory: qemu-kvm security update

An update for qemu-kvm is now available for Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions. Red Hat Product Security has rated this update as having a security impact of Low. A Common Vulnerability Scoring System CVSS base score, which gives a detailed severity rating, is availabl...

OESA-2026-2491 libvncserver security update

libvncserver is a set of programs using the RFB Remote Frame Buffer protocol. They are designed to "export" a frame buffer via net: you set up a server and can connect to it via VNC viewers. If the server supports WebSockets which LibVNCServer does, you can also connect using an in-browser VNC...

qemu-kvm security update

An update is available for qemu-kvm. This update affects Rocky Linux 9. A Common Vulnerability Scoring System CVSS base score, which gives a detailed severity rating, is available for each vulnerability from the CVE list Kernel-based Virtual Machine KVM is a full virtualization solution for Linux...