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CVE-2017-18922: Libvncserver Project: Buffer overflow
CVE-2017-18922 is rated critical with a CVSS v3.1 base score of 9.8 and affects Libvncserver Project, along with 9 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.
Vulnerability description
It was discovered that websockets.c in LibVNCServer prior to 0.9.12 did not properly decode certain WebSocket frames. A malicious attacker could exploit this by sending specially crafted WebSocket frames to a server, causing a heap-based buffer overflow.
Severity breakdown
CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
- Attack complexity: Low. No special conditions; the attack can be repeated reliably.
- Privileges required: None. No account or prior access is needed.
- User interaction: None. No action from any user is needed.
- Scope: Unchanged. Impact stays within the vulnerable component.
- Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
- Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
- Availability impact: High. Total loss of availability; the component can be shut down.
Underlying weakness
CWE-787: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
Affected products
- Libvncserver Project: before 0.9.12
- Canonical Ubuntu Linux: 16.04; 18.04; 19.10; 20.04
- Opensuse Leap: 15.1; 15.2
- Fedoraproject: 31; 32
- Siemens Simatic Itc1500 Firmware: from 3.0.0.0 before 3.2.1.0
- Siemens Simatic Itc1500 Pro Firmware: from 3.0.0.0 before 3.2.1.0
- Siemens Simatic Itc1900 Firmware: from 3.0.0.0 before 3.2.1.0
- Siemens Simatic Itc1900 Pro Firmware: from 3.0.0.0 before 3.2.1.0
- Siemens Simatic Itc2200 Firmware: from 3.0.0.0 before 3.2.1.0
- Siemens Simatic Itc2200 Pro Firmware: from 3.0.0.0 before 3.2.1.0
References
- https://cert-portal.siemens.com/productcert/pdf/ssa-390195.pdf
- https://github.com/LibVNC/libvncserver/commit/aac95a9dcf4bbba87b76c72706c3221a842ca433
- https://usn.ubuntu.com/4407-1/
- http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00020.html
- http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00028.html
- 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
- http://www.openwall.com/lists/oss-security/2020/06/30/3
- https://bugzilla.redhat.com/show_bug.cgi?id=1852356
- https://www.openwall.com/lists/oss-security/2020/06/30/2
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4F6FUH4EFK4NAP6GT4TQRTBKWIRCZLIY/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NVP7TJVYJDXDFRHVQ3ENEN3H354QPXEZ/