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CVE-2018-21247

26
FAUCET Score

CVE-2018-21247 is an information leak vulnerability in LibVNCServer versions prior to 0.9.13, specifically within the ConnectToRFBRepeater function in libvncclient/rfbproto.c, affecting products from vendors like Canonical, Debian, and Siemens. With a CVSS score of 7.5 (High), this vulnerability allows an unauthenticated attacker to remotely access uninitialized memory contents, potentially leading to sensitive information disclosure. Despite its high severity, there is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
<= 0.9.12CPE matchmatch criteria
cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:*
14.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
16.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
16.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
18.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.36%
Probability of exploitation in next 30 days
EPSS Percentile
82.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0236 is in the 68th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

github_advisorypatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: libvncserver-0:0.9.11-17.el8
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: libvncserver

Vendor Advisories (1)

redhatCVE-2018-21247Moderate

libvncserver: uninitialized memory contents are vulnerable to Information Leak

Jun 17, 2020

References

lists.opensuse.org / opensuse-security-announce/2020-07/msg00033.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-security-announce/2020-07/msg00055.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-security-announce/2020-07/msg00066.html
Mailing ListThird Party Advisory
cert-portal.siemens.com / productcert/pdf/ssa-390195.pdf
PatchThird Party Advisory
github.com / LibVNC/libvncserver/compare/LibVNCServer-0.9.12...LibVNCServer-0.9.13
PatchThird Party Advisory
github.com / LibVNC/libvncserver/issues/253
Issue TrackingThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/4F6FUH4EFK4NAP6GT4TQRTBKWIRCZLIY
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/NVP7TJVYJDXDFRHVQ3ENEN3H354QPXEZ