How severe is CVE-2018-6307?

CVE-2018-6307 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-6307 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 27% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-6307?

CVE-2018-6307 primarily affects Libvnc Project Libvncserver. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-6307?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-6307 published?

CVE-2018-6307 was published on 2018-12-19 and last updated on 2026-06-17.

CVE-2018-6307

CVE-2018-6307 is a high-severity vulnerability in Libvnc Project Libvncserver with a CVSS 3.x base score of 8.1. Its EPSS exploit-prediction score of 27% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-416.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 6.8
EPSS exploit prediction: 27% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-416
Affected product: Libvnc Project Libvncserver
Published: 2018-12-19
Last modified: 2026-06-17

Description

LibVNC before commit ca2a5ac02fbbadd0a21fabba779c1ea69173d10b contains heap use-after-free vulnerability in server code of file transfer extension that can result remote code execution.

Frequently asked questions

What is CVE-2018-6307?: LibVNC before commit ca2a5ac02fbbadd0a21fabba779c1ea69173d10b contains heap use-after-free vulnerability in server code of file transfer extension that can result remote code execution.
How severe is CVE-2018-6307?: CVE-2018-6307 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-6307 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 27% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-6307?: CVE-2018-6307 primarily affects Libvnc Project Libvncserver. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-6307?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-6307 published?: CVE-2018-6307 was published on 2018-12-19 and last updated on 2026-06-17.

References

Affected products (7)

cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

More vulnerabilities in Libvnc Project Libvncserver

CVE-2019-20788 — Critical (CVSS 9.8): libvncclient/cursor.c in LibVNCServer through 0.9.12 has a HandleCursorShape integer overflow and heap-based buffer…
CVE-2018-20750 — Critical (CVSS 9.8): LibVNC through 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The fix for…
CVE-2018-20749 — Critical (CVSS 9.8): LibVNC before 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The fix for…
CVE-2018-20748 — Critical (CVSS 9.8): LibVNC before 0.9.12 contains multiple heap out-of-bounds write vulnerabilities in libvncclient/rfbproto.c. The fix for…
CVE-2018-20020 — Critical (CVSS 9.8): LibVNC before commit 7b1ef0ffc4815cab9a96c7278394152bdc89dc4d contains heap out-of-bound write vulnerability inside…
CVE-2018-20019 — Critical (CVSS 9.8): LibVNC before commit a83439b9fbe0f03c48eb94ed05729cb016f8b72f contains multiple heap out-of-bound write vulnerabilities…

All CVEs affecting Libvnc Project Libvncserver →

Other CWE-416 (Use After Free) vulnerabilities

CVE-2026-13782 — Critical (CVSS 10.0): Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…

Browse all CWE-416 (Use After Free) vulnerabilities →