LibVNCServer up to 0.9.11 WebSocket Frame websockets.c out-of-bounds write

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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A vulnerability was found in LibVNCServer up to 0.9.11 and classified as very critical. This issue affects some unknown processing of the file websockets.c of the component WebSocket Frame Handler. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. Using CWE to declare the problem leads to CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

It was discovered that websockets.c in LibVNCServer prior to 0.9.12 did not properly decode certain WebSocket frames. A malicious attacker could exploit this by sending specially crafted WebSocket frames to a server, causing a heap-based buffer overflow.

The weakness was presented 04/22/2023. The advisory is shared at The identification of this vulnerability is CVE-2017-18922 since 06/30/2020. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/22/2023).

Upgrading to version 0.9.12 eliminates this vulnerability. Applying the patch aac95a9dcf4bbba87b76c72706c3221a842ca433 is able to eliminate this problem. The bugfix is ready for download at The best possible mitigation is suggested to be upgrading to the latest version.

See VDB-144419, VDB-144420 and VDB-154302 for similar entries.





CPE 2.3info

CPE 2.2info


VulDB CVSS-B Score: 🔍
VulDB CVSS-BT Score: 🔍
VulDB Vector: 🔍
VulDB Reliability: 🔍


VulDB Meta Base Score: 9.8
VulDB Meta Temp Score: 9.6

VulDB Base Score: 9.8
VulDB Temp Score: 9.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔍



VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍


Class: Out-of-bounds write
CWE: CWE-787 / CWE-119

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍


Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍


Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: LibVNCServer 0.9.12
Patch: aac95a9dcf4bbba87b76c72706c3221a842ca433


06/30/2020 🔍
04/21/2023 +1025 days 🔍
04/22/2023 +0 days 🔍
05/15/2023 +23 days 🔍


Advisory: USN-4407-1
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2017-18922 (🔍)
See also: 🔍


Created: 04/22/2023 12:54 AM
Updated: 05/15/2023 04:32 PM
Changes: 04/22/2023 12:54 AM (59), 05/15/2023 04:32 PM (1)
Complete: 🔍
Cache ID: 44:9F0:40


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