CVE-2021-42785
CRITICALCVSS 9.8/10EPSS 2.27%
Last modified
CVE-2021-42785 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 2.27% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Tightvnc | Tightvnc | <= 2.8.59 |
References
- https://www.tightvnc.com/whatsnew.phpRelease Notes, Vendor Advisory
- https://www.tightvnc.com/whatsnew.phpRelease Notes, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is 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.
How severe is CVE-2021-42785?
CVE-2021-42785 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.27% probability of exploitation in the next 30 days.
How do I fix CVE-2021-42785?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-42785?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST