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CVE-2018-20750

33
FAUCET Score

CVE-2018-20750 is a critical heap out-of-bounds write vulnerability in LibVNC through version 0.9.12, specifically within libvncserver/rfbserver.c, affecting products from Canonical, Debian, LibVNC Project, and Siemens. This vulnerability has a CVSS score of 9.8, indicating a critical severity due to its network-based attack vector, low attack complexity, and high potential for confidentiality, integrity, and availability impacts. While there is no evidence of active exploitation, nor publicly available exploit code in Metasploit, Nuclei, or ExploitDB, the vulnerability has garnered significant community discussion with 10 mentions, placing it in the top 1% of CVEs for community attention.

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

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.33%
Probability of exploitation in next 30 days
EPSS Percentile
87.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0333 is in the 79th percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: libvncserver

Vendor Advisories (1)

redhatCVE-2018-20750Important

libvncserver: Heap out-of-bounds write in rfbserver.c in rfbProcessFileTransferReadBuffer() allows for potential code execution (Incomplete fix for CVE-2018-15127)

Jan 6, 2019

References

cert-portal.siemens.com / productcert/pdf/ssa-390195.pdf
PatchThird Party Advisory
github.com / LibVNC/libvncserver/commit/09e8fc02f59f16e2583b34fe1a270c238bd9ffec
PatchThird Party Advisory
github.com / LibVNC/libvncserver/issues/273
Issue TrackingThird Party Advisory
lists.debian.org / debian-lts-announce/2019/01/msg00029.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2019/10/msg00042.html
Mailing ListThird Party Advisory
usn.ubuntu.com / 3877-1
Third Party Advisory
usn.ubuntu.com / 4547-1
Third Party Advisory
usn.ubuntu.com / 4587-1
Third Party Advisory
openwall.com / lists/oss-security/2018/12/10/8
ExploitMailing ListThird Party Advisory
securityfocus.com / bid/106825
Broken Link