Vulnerability identifier: #VU50841

Vulnerability risk: Low

CVSSv3.1: 6.1 [CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: N/A

CWE-ID: CWE-362

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Zstandard
Universal components / Libraries / Libraries used by multiple products

Vendor: Facebook Inc.

Description

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

The vulnerability exists due to a race condition when creating files. The application creates a files with the default umask before chmod'ing to down to 0600. A local user can exploit the race and gain unauthorized access to sensitive information and escalate privileges on the system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Zstandard: 1.4.0 - 1.4.8, 1.3.0 - 1.3.8, 1.2.0, 1.1.0 - 1.1.4, 1.0.0

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External links
http://github.com/facebook/zstd/issues/2491
http://github.com/facebook/zstd/commit/a774c5797399040af62db21d8a9b9769e005430e

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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.