How severe is CVE-2016-9942?

CVE-2016-9942 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-9942 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-9942?

CVE-2016-9942 affects Libvncserver Project Libvncserver. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-9942?

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

When was CVE-2016-9942 published?

CVE-2016-9942 was published on 2016-12-31 and last updated on 2026-06-17.

CVE-2016-9942

CVE-2016-9942 is a critical-severity vulnerability in Libvncserver Project Libvncserver with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-119.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 4% (89th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-119
Affected product: Libvncserver Project Libvncserver
Published: 2016-12-31
Last modified: 2026-06-17

Description

Heap-based buffer overflow in ultra.c in LibVNCClient in LibVNCServer before 0.9.11 allows remote servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted FramebufferUpdate message with the Ultra type tile, such that the LZO payload decompressed length exceeds what is specified by the tile dimensions.

Frequently asked questions

What is CVE-2016-9942?: Heap-based buffer overflow in ultra.c in LibVNCClient in LibVNCServer before 0.9.11 allows remote servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted FramebufferUpdate message with the Ultra type tile, such that the LZO payload decompressed length exceeds what is specified by the tile dimensions.
How severe is CVE-2016-9942?: CVE-2016-9942 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2016-9942 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-9942?: CVE-2016-9942 affects Libvncserver Project Libvncserver. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-9942?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2016-9942 published?: CVE-2016-9942 was published on 2016-12-31 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:libvncserver_project:libvncserver:0.9.10:*:*:*:*:*:*:*

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