CVE-2021-42785
CVE-2021-42785 is a critical-severity vulnerability in Tightvnc with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- CVSS v2: 7.5
- EPSS exploit prediction: 2% (81st percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-120
- Affected product: Tightvnc
- Published:
- Last modified:
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.
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 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-42785 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (81st percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-42785?
- CVE-2021-42785 affects Tightvnc. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-42785?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2021-42785 published?
- CVE-2021-42785 was published on 2021-11-23 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:tightvnc:tightvnc:*:*:*:*:*:*:*:*
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