UltraVNC Viewer 1.2.2.4 contains a denial of service vulnerability that allows attackers to crash the application by supplying an oversized string to the VNC Server input field. Attackers can paste a malicious string containing 256 repeated characters into the VNC Server field and click Connect to trigger a buffer overflow that crashes the viewer.

OpenClaw versions prior to 2026.2.21 sandbox browser entrypoint launches x11vnc without authentication for noVNC observer sessions, allowing unauthenticated access to the VNC interface. Remote attackers on the host loopback interface can connect to the exposed noVNC port to observe or interact with the sandbox browser without credentials.

openclaw

A weakness has been identified in UltraVNC 1.6.4.0 on Windows. This affects an unknown function in the library cryptbase.dll of the component Windows Service. This manipulation causes uncontrolled search path. The attack requires local access. A high degree of complexity is needed for the attack. The exploitability is reported as difficult. The vendor was contacted early about this disclosure but did not respond in any way.

uvnc · microsoft

Incorrect access control in the VNC component of Weintek cMT-3072XH2 easyweb v2.1.53, OS v20231011 allows unauthorized attackers to access the HMI system.

weintek

UltraVNC Viewer 1.2.4.0 contains a denial of service vulnerability that allows attackers to crash the application by manipulating VNC Server input. Attackers can generate a malformed 256-byte payload and paste it into the VNC Server connection dialog to trigger an application crash.

UltraVNC Launcher 1.2.4.0 contains a denial of service vulnerability in the Repeater Host configuration field that allows attackers to crash the application. Attackers can paste an overly long string of 300 characters into the Repeater Host property to trigger an application crash.

uvnc

UltraVNC Launcher 1.2.4.0 contains a denial of service vulnerability in its password configuration properties that allows local attackers to crash the application. Attackers can paste an overly long 300-character string into the password field to trigger an application crash and prevent normal launcher functionality.

uvnc

A flaw was found in QEMU. If the QIOChannelWebsock object is freed while it is waiting to complete a handshake, a GSource is leaked. This can lead to the callback firing later on and triggering a use-after-free in the use of the channel. This can be abused by a malicious client with network access to the VNC WebSocket port to cause a denial of service during the WebSocket handshake prior to the VNC client authentication.

Open OnDemand is an open-source HPC portal. Prior to versions 3.1.15 and 4.0.7, noVNC interactive applications did not correctly rotate the password when TurboVNC was higher than version 3.1.2. The likelihood of exploitation is low as a user would need to share their link to an active desktop session and the other user would need to be authenticated to the portal. But obtaining the link would allow that user to perform any actions as the original user and access their data. Open OnDemand 3.1.15 and 4.0.7 have patched this vulnerability and correctly rotate passwords for any version of TurboVNC. As a workaround, downgrade TurboVNC to a version lower than 3.1.2.

An Integer Overflow or Wraparound vulnerability [CWE-190] in FortiOS version 7.6.2 and below, version 7.4.7 and below, version 7.2.10 and below, 7.2 all versions, 6.4 all versions, FortiProxy version 7.6.2 and below, version 7.4.3 and below, 7.2 all versions, 7.0 all versions, 2.0 all versions and FortiPAM version 1.5.0, version 1.4.2 and below, 1.3 all versions, 1.2 all versions, 1.1 all versions, 1.0 all versions SSL-VPN RDP and VNC bookmarks may allow an authenticated user to affect the device SSL-VPN availability via crafted requests.

fortinet

A vulnerability has been identified in SINUMERIK 828D PPU.4 (All versions < V4.95 SP5), SINUMERIK 828D PPU.5 (All versions < V5.25 SP1), SINUMERIK 840D sl (All versions < V4.95 SP5), SINUMERIK MC (All versions < V1.25 SP1), SINUMERIK MC V1.15 (All versions < V1.15 SP5), SINUMERIK ONE (All versions < V6.25 SP1), SINUMERIK ONE V6.15 (All versions < V6.15 SP5). The affected application improperly validates authentication for its VNC access service, allowing access with insufficient password verification. This could allow an attacker to gain unauthorized remote access and potentially compromise system confidentiality, integrity, or availability.

The VNC application stores its passwords encrypted within the registry but uses DES for encryption. As DES is broken, the original passwords can be recovered.

endress

The VNC authentication mechanism bases on a challenge-response system where both server and client use the same password for encryption. The challenge is sent from the server to the client, is encrypted by the client and sent back. The server does the same encryption locally and if the responses match it is prooven that the client knows the correct password. Since all VNC communication is unencrypted, an attacker can obtain the challenge and response and try to derive the password from this information.

endress

All communication between the VNC server and client(s) is unencrypted. This allows an attacker to intercept the traffic and obtain sensitive data.

endress

The CS5000 Fire Panel is vulnerable due to a hard-coded password that runs on a VNC server and is visible as a string in the binary responsible for running VNC. This password cannot be altered, allowing anyone with knowledge of it to gain remote access to the panel. Such access could enable an attacker to operate the panel remotely, potentially putting the fire panel into a non-functional state and causing serious safety issues.

Jupyter Remote Desktop Proxy allows you to run a Linux Desktop on a JupyterHub. 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 TurboVNC as the vncserver executable. This issue is fixed in 3.0.1.

LibVNCServer 0.9.12 release and earlier contains heap buffer overflow vulnerability within the HandleCursorShape() function in libvncclient/cursor.c. An attacker sends cursor shapes with specially crafted dimensions, which can result in remote code execution.

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix TSO DMA API usage causing oops Commit 66600fac7a98 ("net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data") moved the assignment of tx_skbuff_dma[]'s members to be later in stmmac_tso_xmit(). The buf (dma cookie) and len stored in this structure are passed to dma_unmap_single() by stmmac_tx_clean(). The DMA API requires that the dma cookie passed to dma_unmap_single() is the same as the value returned from dma_map_single(). However, by moving the assignment later, this is not the case when priv->dma_cap.addr64 > 32 as "des" is offset by proto_hdr_len. This causes problems such as: dwc-eth-dwmac 2490000.ethernet eth0: Tx DMA map failed and with DMA_API_DEBUG enabled: DMA-API: dwc-eth-dwmac 2490000.ethernet: device driver tries to +free DMA memory it has not allocated [device address=0x000000ffffcf65c0] [size=66 bytes] Fix this by maintaining "des" as the original DMA cookie, and use tso_des to pass the offset DMA cookie to stmmac_tso_allocator(). Full details of the crashes can be found at: https://lore.kernel.org/all/d8112193-0386-4e14-b516-37c2d838171a@nvidia.com/ https://lore.kernel.org/all/klkzp5yn5kq5efgtrow6wbvnc46bcqfxs65nz3qy77ujr5turc@bwwhelz2l4dw/

linux

server.c in Neat VNC (aka neatvnc) before 0.8.1 does not properly validate the security type, a related issue to CVE-2006-2369.

any1

TightVNC (Server for Windows) before 2.8.84 allows attackers to connect to the control pipe via a network connection.

A Directory Traversal vulnerability in KasmVNC 1.3.1.230e50f7b89663316c70de7b0e3db6f6b9340489 and possibly earlier versions allows remote authenticated attackers to browse parent directories and read the content of files outside the scope of the application.

A flaw was found in the QEMU built-in VNC server while processing ClientCutText messages. The qemu_clipboard_request() function can be reached before vnc_server_cut_text_caps() was called and had the chance to initialize the clipboard peer, leading to a NULL pointer dereference. This could allow a malicious authenticated VNC client to crash QEMU and trigger a denial of service.

qemu · redhat