Vulnerability database
Every flaw the U.S. government’s cybersecurity agency (CISA) has confirmed attackers are using, plus the new WordPress plugin and theme bugs published each day, sorted by what they mean for a small business. We refresh it twice a day. If you see something your website or office runs, tell us.
11 results
Oct 8, 2026An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server to reCVE-2026-107611 · Other software · GlavSoft · reported by 33c584b5-0579-4c06-b2a0-8d8329fcab9cHigh 7.1
An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server to read heap memory beyond the palette allocation and crash the viewer by sending ZRLE-encoded tiles whose palette indices exceed the declared palette size. readPaletteRleTile() and readPackedPaletteTile() use the attacker-supplied index to look up colours without validating it against the palette size; out-of-bounds heap data is copied into the framebuffer (garbled display) or the read faults, terminating the viewer.
- Product
- TightVNC
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordsourceforge.nettightvnc.com
Jul 1, 2026UltraVNC viewer through 1.8.2.2 contains an integer overflow leading to a heap buffer overflow in the RFB protocol failure-response parsing path.CVE-2026-7838 · Other software · uvnc · reported by 33c584b5-0579-4c06-b2a0-8d8329fcab9cHigh 8.7
UltraVNC viewer through 1.8.2.2 contains an integer overflow leading to a heap buffer overflow in the RFB protocol failure-response parsing path. In vncviewer/ClientConnection.cpp, the 4-byte network-supplied reasonLen field (type CARD32) is passed as reasonLen+1 to CheckBufferSize(). Because both operands are unsigned 32-bit, a reasonLen of 0xFFFFFFFF overflows to 0, causing CheckBufferSize to allocate only 256 bytes. The subsequent ReadString(m_netbuf, reasonLen) call then performs ReadExact for the original 4 GiB length into that 256-byte heap buffer. This overflow is reachable via rfbConnFailed (auth-scheme negotiation) and rfbVncAuthFailed (post-handshake) message types without successful authentication. A malicious VNC server, or any man-in-the-middle on the RFB stream, can trigger this condition when the victim viewer connects, potentially resulting in remote code execution as the user running the viewer. The crash was confirmed with AddressSanitizer on a portable reproduction harness (heap-buffer-overflow WRITE at offset 256).
- Product
- UltraVNC
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Jul 1, 2026UltraVNC viewer through 1.8.2.2 contains an off-by-one stack buffer overflow in the RFB ServerInit message handler.CVE-2026-7831 · Other software · uvnc · reported by 33c584b5-0579-4c06-b2a0-8d8329fcab9cHigh 7.6
UltraVNC viewer through 1.8.2.2 contains an off-by-one stack buffer overflow in the RFB ServerInit message handler. In vncviewer/ClientConnection.cpp, when the server-supplied nameLength equals exactly 2024 the code declares a 2024-byte stack buffer _dn[2024] and calls ReadString(_dn, 2024). ReadString writes the NUL terminator at buf[length], i.e., _dn[2024], one byte past the end of the stack buffer. A malicious VNC server can trigger this condition by advertising a desktop name of length 2024 in its ServerInit message. On release builds without stack canaries the single-byte NUL overwrite adjacent stack data. On builds with /GS stack protection the canary is corrupted and the process terminates, resulting in denial of service. User interaction (connecting the viewer to the malicious server) is required.
- Product
- UltraVNC
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Mar 22, 2026UltraVNC 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 SeCVE-2019-25600 · Other software · Uvnc · reported by VulnCheckHigh 7.1
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.
- Product
- UltraVNC Viewer
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordexploit-db.comuvnc.com
Feb 5, 2026UltraVNC Viewer 1.2.4.0 contains a denial of service vulnerability that allows attackers to crash the application by manipulating VNC Server input.CVE-2020-37134 · Other software · UltraVNC Team · reported by VulnCheckMedium 4.6
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.
- Product
- UltraVNC Viewer
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordexploit-db.comuvnc.com
Sep 30, 2022RealVNC VNC Server before 6.11.0 and VNC Viewer before 6.22.826 on Windows allow local privilege escalation via MSI installer Repair mode.CVE-2022-41975 · Other software · Realvnc · reported by MITREHigh 7.8
RealVNC VNC Server before 6.11.0 and VNC Viewer before 6.22.826 on Windows allow local privilege escalation via MSI installer Repair mode.
- Product
- VNC Server
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordhelp.realvnc.comhelp.realvnc.com
Nov 23, 2021Buffer Overflow vulnerability in tvnviewer.exe of TightVNC Viewer allows a remote attacker to execute arbitrary instructions via a crafted FramebufferUpdate pacCVE-2021-42785 · Other software · GlavSoft LLC · reported by cve_disclosure@tech.gov.sgCritical 9.8
Buffer Overflow vulnerability in tvnviewer.exe of TightVNC Viewer allows a remote attacker to execute arbitrary instructions via a crafted FramebufferUpdate packet from a VNC server.
- Product
- TightVNC Viewer
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordtightvnc.comtightvnc.com
Sep 17, 2021RealVNC Viewer 6.21.406 allows remote VNC servers to cause a denial of service (application crash) via crafted RFB protocol data.CVE-2021-41380 · Other software · Realvnc · reported by MITREMedium 6.5
RealVNC Viewer 6.21.406 allows remote VNC servers to cause a denial of service (application crash) via crafted RFB protocol data. NOTE: It is asserted that this issue requires social engineering a user into connecting to a fake VNC Server. The VNC Viewer application they are using will then hang, until terminated, but no memory leak occurs - the resources are freed once the hung process is terminated and the resource usage is constant during the hang. Only the process that is connected to the fake Server is affected. This is an application bug, not a security issue
- Product
- VNC Viewer
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordgist.github.comgist.github.com
Jan 16, 2009The CMsgReader::readRect function in the VNC Viewer component in RealVNC VNC Free Edition 4.0 through 4.1.2, Enterprise Edition E4.0 through E4.4.2, and PersonaCVE-2008-4770 · Other software · Realvnc · reported by MITREHigh 10
The CMsgReader::readRect function in the VNC Viewer component in RealVNC VNC Free Edition 4.0 through 4.1.2, Enterprise Edition E4.0 through E4.4.2, and Personal Edition P4.0 through P4.4.2 allows remote VNC servers to execute arbitrary code via crafted RFB protocol data, related to "encoding type."
- Product
- Realvnc
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordsecunia.comsecunia.com
Sep 16, 2008Remote Management and Screen Sharing in Apple Mac OS X 10.5 through 10.5.4, when used to set a password for a VNC viewer, displays additional input characters bCVE-2008-3617 · Computers, phones & browsers · Apple · reported by MITREMedium 5
Remote Management and Screen Sharing in Apple Mac OS X 10.5 through 10.5.4, when used to set a password for a VNC viewer, displays additional input characters beyond the maximum password length, which might make it easier for attackers to guess passwords that the user believed were longer.
- Product
- MAC OS X
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordlists.apple.comsecuritytracker.com
May 8, 2007Heap-based buffer overflow in the ConnectAsyncEx function in VNC Viewer ActiveX control (scvncctrl.dll) in the SmartCode VNC Manager 3.6 allows remote attackersCVE-2007-2526 · Other software · Smartcode · reported by MITREHigh 9.3
Heap-based buffer overflow in the ConnectAsyncEx function in VNC Viewer ActiveX control (scvncctrl.dll) in the SmartCode VNC Manager 3.6 allows remote attackers to execute arbitrary code via a long argument.
- Product
- VNC Manager
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordmoaxb.blogspot.comosvdb.org
Where this comes from: the exploited list is CISA’s Known Exploited Vulnerabilities catalog. Everything else is the whole National Vulnerability Database, where each record is published by the team that found the bug (Wordfence, Patchstack, WPScan, the vendors themselves and others); we show who. Exploit odds are FIRST’s EPSS, updated daily. Titles and categories are ours, so check the linked record before acting on a detail. For a write-up of the big ones, see our advisories. Every vendor, and every WordPress plugin and theme with a recorded flaw, also has its own page. All of it is free to reuse as JSON, CSV or RSS.
Weekly security brief
The flaws that hit local websites, every Friday.
One short email: what got exploited this week, which WordPress plugins broke, and what to check. Unsubscribe in one click.
Tell us what you're building.
A website, your marketing, a security check, an app, or the thing you've been running out of a spreadsheet for three years. A few lines is plenty.
Not ready to talk yet? Run the free website check and see what Google sees.