CVE-2021-42785
Buffer Overflow in tvnviewer.exe via Crafted Packet in TightVNC Viewer 2.8.59
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2021-42785- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-120
- Updated
- 2026-11-02
CVE List No score
Buffer Overflow in tvnviewer.exe via Crafted Packet in TightVNC Viewer 2.8.59
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.
- Record
CVE-2021-42785- Weakness
- CWE-120
- Updated
- 2026-11-02
EUVDEUVD-2021-29741 No score
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.
- Record
EUVD-2021-29741- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-7q87-cj95-29mc No score
Buffer Overflow vulnerability in tvnviewer.exe of TightVNC Viewer allows a remote attacker to...
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.
- Record
GHSA-7q87-cj95-29mc- Weakness
- CWE-120
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2021-42785
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.
- Record
UBUNTU-CVE-2021-42785- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
tightvncUbuntu:16.04:LTS |
All versions, plus listed versions 1.3.10-0ubuntu21.3.10-0ubuntu3 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-42785 is a critical vulnerability (CVSS 9.8) in Glavsoft Llc Tightvnc Viewer, published November 23, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.34%, the 83rd percentile. No source names a fixed version.