VDB-130338 · CVE-2018-20749 · DLA 1617-1

LibVNCServer up to 0.9.11 libvncserver/rfbserver.c out-of-bounds write

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.4	$0-$5k	0.00

Summaryinfo

A vulnerability described as critical has been identified in LibVNCServer up to 0.9.11. Affected is an unknown function of the file libvncserver/rfbserver.c. The manipulation results in out-of-bounds write. This vulnerability was named CVE-2018-20749. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in LibVNCServer up to 0.9.11. Affected is an unknown code block of the file libvncserver/rfbserver.c. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. CWE is classifying the issue as CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

LibVNC before 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The fix for CVE-2018-15127 was incomplete.

The bug was discovered 12/10/2018. The weakness was presented 01/30/2019 by Solar Designer (Website). The advisory is available at github.com. This vulnerability is traded as CVE-2018-20749 since 01/30/2019. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit.

The vulnerability was handled as a non-public zero-day exploit for at least 51 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 121517 (Debian DLA-1652-1 : libvncserver security update), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Debian Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 197361 (Ubuntu Security Notification for Libvncserver Vulnerabilities (USN-3877-1)).

Upgrading to version 0.9.12 eliminates this vulnerability. A possible mitigation has been published 1 days after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (121517) and SecurityFocus (BID 106825†). See VDB-128103, VDB-128104, VDB-128119 and VDB-128120 for similar entries. If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

LibVNCServer

Version

License

open-source

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.5
VulDB Meta Temp Score: 8.4

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

NVD Base Score: 🔍

Exploitinginfo

Class: Out-of-bounds write
CWE: CWE-787 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 121517
Nessus Name: Debian DLA-1652-1 : libvncserver security update
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Upgrade: LibVNCServer 0.9.12
Patch: github.com

Timelineinfo

12/10/2018 🔍
01/30/2019 +51 days 🔍
01/30/2019 +0 days 🔍
01/30/2019 +0 days 🔍
01/31/2019 +1 days 🔍
01/31/2019 +0 days 🔍
01/31/2019 +0 days 🔍
02/01/2019 +1 days 🔍
07/04/2023 +1614 days 🔍

Sourcesinfo

Advisory: DLA 1617-1
Researcher: Solar Designer
Status: Confirmed

CVE: CVE-2018-20749 (🔍)
GCVE (CVE): GCVE-0-2018-20749
GCVE (VulDB): GCVE-100-130338
SecurityFocus: 106825 - LibVNCServer Incomplete Fix Multiple Heap Buffer Overflow Vulnerabilities

See also: 🔍

Entryinfo

Created: 01/31/2019 13:05
Updated: 07/04/2023 08:49
Changes: 01/31/2019 13:05 (74), 05/06/2020 20:37 (5), 07/04/2023 08:40 (5), 07/04/2023 08:44 (1), 07/04/2023 08:49 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.