VDB-123252 · CVE-2018-15862 · RHSA-2019:2079

xkbcommon up to 0.8.1 Keymap File xkbcomp/expr.c LookupModMask null pointer dereference

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.
4.3	$0-$5k	0.00

Summaryinfo

A vulnerability labeled as problematic has been found in xkbcommon up to 0.8.1. This affects the function LookupModMask of the file xkbcomp/expr.c of the component Keymap File Handler. The manipulation results in null pointer dereference. This vulnerability is reported as CVE-2018-15862. The attack requires a local approach. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in xkbcommon up to 0.8.1. It has been classified as problematic. Affected is the function LookupModMask of the file xkbcomp/expr.c of the component Keymap File Handler. The manipulation with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on availability. CVE summarizes:

Unchecked NULL pointer usage in LookupModMask in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file with invalid virtual modifiers.

The bug was discovered 08/05/2018. The weakness was disclosed 08/25/2018 (Website). The advisory is shared for download at github.com. This vulnerability is traded as CVE-2018-15862 since 08/24/2018. The exploitability is told to be easy. The attack needs to be approached locally. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available.

The vulnerability was handled as a non-public zero-day exploit for at least 20 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 118505 (GLSA-201810-05 : xkbcommon: Multiple vulnerabilities), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Gentoo Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 197271 (Ubuntu Security Notification for Libxkbcommon Vulnerabilities (USN-3786-1)).

Upgrading to version 0.8.2 eliminates this vulnerability. A possible mitigation has been published 3 months after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (118505). The entries VDB-123244, VDB-123245, VDB-123246 and VDB-123247 are pretty similar. Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

xkbcommon

Version

License

open-source

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.3

VulDB Base Score: 3.3
VulDB Temp Score: 3.2
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔍

CVSSv2info

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

NVD Base Score: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

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: 118505
Nessus Name: GLSA-201810-05 : xkbcommon: Multiple vulnerabilities
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: xkbcommon 0.8.2
Patch: github.com

Timelineinfo

08/05/2018 🔍
08/24/2018 +18 days 🔍
08/25/2018 +1 days 🔍
08/25/2018 +0 days 🔍
08/26/2018 +1 days 🔍
10/30/2018 +65 days 🔍
10/31/2018 +1 days 🔍
05/04/2023 +1646 days 🔍

Sourcesinfo

Advisory: RHSA-2019:2079
Status: Confirmed

CVE: CVE-2018-15862 (🔍)
GCVE (CVE): GCVE-0-2018-15862
GCVE (VulDB): GCVE-100-123252
See also: 🔍

Entryinfo

Created: 08/26/2018 08:58
Updated: 05/04/2023 15:18
Changes: 08/26/2018 08:58 (74), 03/18/2020 10:57 (2), 05/04/2023 15:18 (5)
Complete: 🔍
Cache ID: 216::103