Vulnerability record · CVE-2019-8266 · published 8 March 2019

CVE-2019-8266: Uvnc ultravnc out-of-bounds read vulnerability

Uvnc · Ultravnc

UltraVNC revision 1207 has multiple out-of-bounds access vulnerabilities connected with improper usage of ClientConnection::Copybuffer function in VNC client code, which can potentially result in code execution. This attack appears to be exploitable via network connectivity. User interaction is required to trigger these vulnerabilities. These vulnerabilities have been fixed in revision 1208.

9.8 CVSS 3.0 Critical EPSS 2.8% · top 13.9% CWE-788 · CWE-788CWE-125 · Out-of-bounds read

9.8CVSS 3.0 base score, v2 7.5

2.8%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

6References

17 Jun 2026Last modified by NVD

Description

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Ultravnc Uvnc

References

Link	Tags
https://cert-portal.siemens.com/productcert/pdf/ssa-927095.pdf
https://ics-cert.kaspersky.com/advisories/klcert-advisories/2019/03/01/klcert-19-013-ultravnc-access-of-memory-location-	Third Party Advisory
https://www.us-cert.gov/ics/advisories/icsa-20-161-06
https://cert-portal.siemens.com/productcert/pdf/ssa-927095.pdf
https://ics-cert.kaspersky.com/advisories/klcert-advisories/2019/03/01/klcert-19-013-ultravnc-access-of-memory-location-	Third Party Advisory
https://www.us-cert.gov/ics/advisories/icsa-20-161-06

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2019-8264Uvnc ultravnc out-of-bounds read vulnerabilityUltraVNC revision 1203 has out-of-bounds access vulnerability in VNC client inside Ultra2 decoder, which can potentially result in code execution. Th…EPSS 3.1%8 Mar 2019 9.8CVE-2019-8265Uvnc ultravnc out-of-bounds read vulnerabilityUltraVNC revision 1207 has multiple out-of-bounds access vulnerabilities connected with improper usage of SETPIXELS macro in VNC client code, which c…EPSS 3.1%8 Mar 2019 9.8CVE-2019-8268Uvnc ultravnc vulnerabilityUltraVNC revision 1206 has multiple off-by-one vulnerabilities in VNC client code connected with improper usage of ClientConnection::ReadString funct…EPSS 3.9%8 Mar 2019 9.8CVE-2019-8271Uvnc ultravnc heap-based buffer overflow vulnerabilityUltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer handler, which can potentially result code ex…EPSS 8.3%8 Mar 2019 9.8CVE-2019-8272Uvnc ultravnc vulnerabilityUltraVNC revision 1211 has multiple off-by-one vulnerabilities in VNC server code, which can potentially result in code execution. This attack appear…EPSS 3.9%8 Mar 2019 9.8CVE-2019-8273Uvnc ultravnc heap-based buffer overflow vulnerabilityUltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer request handler, which can potentially result…EPSS 8.3%8 Mar 2019 9.8CVE-2019-8274Uvnc ultravnc heap-based buffer overflow vulnerabilityUltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer offer handler, which can potentially in resul…EPSS 8.3%8 Mar 2019 9.8CVE-2019-8275Uvnc ultravnc vulnerabilityUltraVNC revision 1211 has multiple improper null termination vulnerabilities in VNC server code, which result in out-of-bound data being accessed by…EPSS 4.0%8 Mar 2019

Source: NIST National Vulnerability Database (record CVE-2019-8266), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.