Remote code execution in GNU Screen



Risk High
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-26937
CWE-ID CWE-88
Exploitation vector Network
Public exploit N/A
Vulnerable software
 Screen
Other software / Other software solutions

Vendor GNU

Security Bulletin

This security bulletin contains one high risk vulnerability.

1) Improper Neutralization of Argument Delimiters in a Command

EUVDB-ID: #VU50842

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 - Argument Injection or Modification

Exploit availability: No

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

CPE2.3 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


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.



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