What’s Vulnerable › Vulnerabilities

CVE-2019-20840

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-06-17 · updated 2026-06-17
• Weakness: CWE-787

Description

An issue was discovered in LibVNCServer before 0.9.13. libvncserver/ws_decode.c can lead to a crash because of unaligned accesses in hybiReadAndDecode.

Affected products

• Canonical Ubuntu Linux: 14.04, 16.04, 18.04, 18.10, 20.04
• Debian Linux: 8.0, 9.0
• Libvnc Project Libvncserver: through 0.9.12
• openSUSE Leap: 15.2
• Siemens Simatic Itc1500 Firmware: from 3.0.0.0 before 3.2.1.0 — fixed in 3.2.1.0
• Siemens Simatic Itc1500 Pro Firmware: from 3.0.0.0 before 3.2.1.0 — fixed in 3.2.1.0
• Siemens Simatic Itc1900 Firmware: from 3.0.0.0 before 3.2.1.0 — fixed in 3.2.1.0
• Siemens Simatic Itc1900 Pro Firmware: from 3.0.0.0 before 3.2.1.0 — fixed in 3.2.1.0
• Siemens Simatic Itc2200 Firmware: from 3.0.0.0 before 3.2.1.0 — fixed in 3.2.1.0
• Siemens Simatic Itc2200 Pro Firmware: from 3.0.0.0 before 3.2.1.0 — fixed in 3.2.1.0

How to fix

Upgrade to a fixed version: Siemens Simatic Itc1500 Firmware 3.2.1.0; Siemens Simatic Itc1500 Pro Firmware 3.2.1.0; Siemens Simatic Itc1900 Firmware 3.2.1.0; Siemens Simatic Itc1900 Pro Firmware 3.2.1.0; Siemens Simatic Itc2200 Firmware 3.2.1.0; Siemens Simatic Itc2200 Pro Firmware 3.2.1.0. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00033.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00055.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00066.html
• https://cert-portal.siemens.com/productcert/pdf/ssa-390195.pdf
• https://github.com/LibVNC/libvncserver/commit/0cf1400c61850065de590d403f6d49e32882fd76
• https://github.com/LibVNC/libvncserver/compare/LibVNCServer-0.9.12...LibVNCServer-0.9.13
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4F6FUH4EFK4NAP6GT4TQRTBKWIRCZLIY/
• https://usn.ubuntu.com/4434-1/
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00033.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00055.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00066.html
• https://cert-portal.siemens.com/productcert/pdf/ssa-390195.pdf

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