#VU50842 Improper Neutralization of Argument Delimiters in a Command in Screen - CVE-2021-26937

Vulnerability identifier: #VU50842

Vulnerability risk: High

CVSSv4.0: 6.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2021-26937

CWE-ID: CWE-88

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Screen
Other software / Other software solutions

Vendor: GNU

Description

The vulnerability allows a remote attacker to compromise the affected system.

The vulnerability exists due to incorrect processing of user-supplied data in the encoding.c file. A remote attacker can pass specially crafted UTF-8 character sequence to the GNU Screen application and perform a denial of service attack or execute arbitrary code on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Screen: 4.0.1 - 4.8.0

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External links
https://www.openwall.com/lists/oss-security/2021/02/09/8
https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html
https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html
https://www.openwall.com/lists/oss-security/2021/02/09/3

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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