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Vulnerability details: VCID-1mc5-8kc9-r7fh
Vulnerability ID VCID-1mc5-8kc9-r7fh
Aliases CVE-2019-20840
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 6.8
Risk 3.4
Affected and Fixed Packages Package Details
Weaknesses (2)
CWE-787 Out-of-bounds Write
CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
System Score Found at
cvssv3 7.5 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-20840.json
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
epss 0.01815 https://api.first.org/data/v1/epss?cve=CVE-2019-20840
cvssv3.1 7.5 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 5.0 https://nvd.nist.gov/vuln/detail/CVE-2019-20840
cvssv3.1 7.5 https://nvd.nist.gov/vuln/detail/CVE-2019-20840
Reference id Reference type URL
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://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-20840.json
https://api.first.org/data/v1/epss?cve=CVE-2019-20840
https://cert-portal.siemens.com/productcert/pdf/ssa-390195.pdf
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-20840
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
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/
1849881 https://bugzilla.redhat.com/show_bug.cgi?id=1849881
cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*
CVE-2019-20840 https://nvd.nist.gov/vuln/detail/CVE-2019-20840
USN-4434-1 https://usn.ubuntu.com/4434-1/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-20840.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2019-20840
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2019-20840
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.82078
EPSS Score 0.01815
Published At Aug. 10, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:31:33.101484+00:00 Alpine Linux Importer Import https://secdb.alpinelinux.org/v3.22/community.json 37.0.0