CVE-2021-42785 json
Buffer Overflow in tvnviewer.exe via Crafted Packet in TightVNC Viewer 2.8.59
published 2021-11-23 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-29741
- cvss
- 9.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 2.3%
- EPSS 2.3% chance of exploitation in 30 days, percentile 83%
- public exploits
- 0
- none known
Summary
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.
Exploit prediction
2.34% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 7.5 | AV:N/AC:L/Au:N/C:P/I:P/A:P |
Affected products
- GlavSoft LLC TightVNC Viewer
Classification
- Weakness
-
- CWE-120 Buffer Copy without Checking Size of Input
References
-
tightvnc.com
/whatsnew.php
release-notes, vendor-advisory
Sources
- CVE List CVE-2021-42785
- NVD CVE-2021-42785
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.