Vulnerability identifier: #VU59048

Vulnerability risk: Low

CVSSv3.1: 7.7 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-4011

CWE-ID: CWE-787

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
X.org Server
Server applications / Other server solutions

Vendor: X.org

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a boundary error in the SwapCreateRegister() function in the Record extension. A local user can send a specially crafted RecordCreateContext and RecordRegisterClients requests, trigger an out-of-bounds write and execute arbitrary code with elevated privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

X.org Server: 1.20.0 - 21.1.1

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External links
http://seclists.org/oss-sec/2021/q4/156
http://www.zerodayinitiative.com/advisories/ZDI-21-1550/

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.