CVE-2018-20021

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Source
https://cve.org/CVERecord?id=CVE-2018-20021
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2018-20021.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2018-20021
Downstream
DEBIAN (1)
MGASA (2)
openSUSE (2)
SUSE (4)
UBUNTU (1)
Related
openSUSE (2)
SUSE (4)
Published
2018-12-19T16:29:00Z
Modified
2026-10-26T13:03:30Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
[none]
Details

LibVNC before commit c3115350eb8bb635d0fdb4dbbb0d0541f38ed19c contains a CWE-835: Infinite loop vulnerability in VNC client code. Vulnerability allows attacker to consume excessive amount of resources like CPU and RAM

Database specific 
{
    "unresolved_ranges":  [
        {
            "cpes":  [
                "cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:*"
            ],
            "extracted_events":  [
                {
                    "range":  [
                        {
                            "fixed":  "0.9.12"
                        }
                    ],
                    "source":  "CPE_RANGE"
                }
            ],
            "vendor_product":  "libvnc_project:libvncserver"
        },
        {
            "cpes":  [
                "cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*",
                "cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*",
                "cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*",
                "cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*"
            ],
            "extracted_events":  [
                {
                    "range":  [
                        {
                            "introduced":  "14.04"
                        },
                        {
                            "last_affected":  "14.04"
                        },
                        {
                            "introduced":  "16.04"
                        },
                        {
                            "last_affected":  "16.04"
                        },
                        {
                            "introduced":  "18.04"
                        },
                        {
                            "last_affected":  "18.04"
                        },
                        {
                            "introduced":  "18.10"
                        },
                        {
                            "last_affected":  "18.10"
                        }
                    ],
                    "source":  "CPE_STRING"
                }
            ],
            "vendor_product":  "canonical:ubuntu_linux"
        },
        {
            "cpes":  [
                "cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*",
                "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*"
            ],
            "extracted_events":  [
                {
                    "range":  [
                        {
                            "introduced":  "8.0"
                        },
                        {
                            "last_affected":  "8.0"
                        },
                        {
                            "introduced":  "9.0"
                        },
                        {
                            "last_affected":  "9.0"
                        }
                    ],
                    "source":  "CPE_STRING"
                }
            ],
            "vendor_product":  "debian:debian_linux"
        }
    ]
}
References

Affected packages

Git / github.com/libvnc/libvncserver

Affected ranges

Type
GIT
Repo
https://github.com/libvnc/libvncserver
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
c3115350eb8bb635d0fdb4dbbb0d0541f38ed19c
Database specific
Show details 
{
    "extracted_events":  [
        {
            "range":  [
                {
                    "introduced":  "0"
                },
                {
                    "fixed":  "c3115350eb8bb635d0fdb4dbbb0d0541f38ed19c"
                }
            ],
            "source":  "DESCRIPTION"
        }
    ]
}

Affected versions

LibVNCServer-0.*
LibVNCServer-0.9.10
LibVNCServer-0.9.11
LibVNCServer-0.9.8
LibVNCServer-0.9.9
Other
X11VNC_0_9_10
X11VNC_0_9_11
X11VNC_0_9_12
X11VNC_0_9_7
X11VNC_0_9_8
X11VNC_0_9_9
X11VNC_REL_0_9_4
X11VNC_REL_0_9_5
X11VNC_REL_0_9_6

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2018-20021.json"
vanir_signatures 
[
    {
        "deprecated":  false,
        "digest":  {
            "line_hashes":  [
                "111104689860169074387343758626736916955",
                "331920370756008792305441832434690907806",
                "206039648254461884243393087187119234585",
                "310875613742987617501774825012747984085"
            ],
            "threshold":  0.9
        },
        "id":  "CVE-2018-20021-83307168",
        "signature_type":  "Line",
        "signature_version":  "v1",
        "source":  "https://github.com/libvnc/libvncserver/commit/c3115350eb8bb635d0fdb4dbbb0d0541f38ed19c",
        "target":  {
            "file":  "libvncclient/rfbproto.c"
        }
    },
    {
        "deprecated":  false,
        "digest":  {
            "function_hash":  "15319519370788259268751568681089809781",
            "length":  15536
        },
        "id":  "CVE-2018-20021-c32d3c28",
        "signature_type":  "Function",
        "signature_version":  "v1",
        "source":  "https://github.com/libvnc/libvncserver/commit/c3115350eb8bb635d0fdb4dbbb0d0541f38ed19c",
        "target":  {
            "file":  "libvncclient/rfbproto.c",
            "function":  "HandleRFBServerMessage"
        }
    }
]
vanir_signatures_modified 
"2026-10-26T13:03:30Z"