Remote code execution in GNU Screen

Published: 2021-02-22
Risk High
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2021-26937
Exploitation vector Network
Public exploit N/A
Vulnerable software
Other software / Other software solutions

Vendor GNU

Security Advisory

This security advisory describes one high risk vulnerability.

1) Improper Neutralization of Argument Delimiters in a Command

Risk: High

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

CVE-ID: CVE-2021-26937

CWE-ID: CWE-88 - Argument Injection or Modification

Exploit availability: No


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.


Install updates from vendor's website.

Vulnerable software versions

Screen: 4.0.1, 4.0.2, 4.0.3, 4.2.0, 4.2.1, 4.3.0, 4.3.1, 4.4.0, 4.5.0, 4.5.1, 4.6.0, 4.6.1, 4.6.2, 4.7.0, 4.8.0

CPE External links

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.