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CVE-2018-6307

39
FAUCET Score

CVE-2018-6307 is a heap use-after-free vulnerability in the server-side file transfer extension of LibVNC, affecting various distributions of Linux including Debian and Ubuntu, as well as the LibVNCServer project itself. This high-severity vulnerability (CVSS 8.1) allows for remote code execution with high impact on confidentiality, integrity, and availability, requiring no user interaction or privileges, but with high attack complexity. While no active exploitation, Metasploit, Nuclei, or ExploitDB entries are currently reported, the vulnerability has garnered some community discussion and media coverage, indicating awareness. It is not listed in the CISA KEV catalog, and its exploitability is considered inactive.

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:*:*:*:lts:*:*:*
18.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
18.10CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.1HIGH

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
26.54%
Probability of exploitation in next 30 days
EPSS Percentile
97.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.2654 is in the 91st percentile among its peer group of 8,914 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

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 Advisories (1)

redhatCVE-2018-6307Important

libvncserver: Use-after-free in file transfer extension server code allows for potential code execution

Dec 19, 2018

References

github.com / LibVNC/libvncserver/issues/241
Third Party Advisory
ics-cert.kaspersky.com / advisories/klcert-advisories/2018/12/19/klcert-18-026-libvnc-heap-use-after-free
Third Party Advisory
lists.debian.org / debian-lts-announce/2018/12/msg00017.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2019/10/msg00042.html
usn.ubuntu.com / 3877-1
Third Party Advisory
debian.org / security/2019/dsa-4383
Third Party Advisory