CVE-2021-26937

screen: crash when processing combining chars

Severity Score

9.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

encoding.c in GNU Screen through 4.8.0 allows remote attackers to cause a denial of service (invalid write access and application crash) or possibly have unspecified other impact via a crafted UTF-8 character sequence.

El archivo encoding.c en GNU Screen versiones hasta 4.8.0, permite a atacantes remotos causar una denegación de servicio (acceso de escritura no válido y bloqueo de la aplicación) o posiblemente tener otro impacto no especificado por medio de una secuencia de caracteres UTF-8 diseñada

A flaw was found in screen. A specially crafted sequence of combining characters could cause an out of bounds write leading to arbitrary code execution. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

*Credits: N/A

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-02-09 CVE Reserved
2021-02-09 CVE Published
2023-11-08 EPSS Updated
2024-08-03 CVE Updated
2024-08-03 First Exploit
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
CWE-787: Out-of-bounds Write

CAPEC

References (11)

URL	Tag	Source
https://ftp.gnu.org/gnu/screen	Product
https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html	Mailing List

URL	Date	SRC
http://www.openwall.com/lists/oss-security/2021/02/09/8	2024-08-03
https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html	2024-08-03
https://www.openwall.com/lists/oss-security/2021/02/09/3	2024-08-03

URL	Date	SRC

URL	Date	SRC
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM	2023-11-07
https://security.gentoo.org/glsa/202105-11	2023-11-07
https://www.debian.org/security/2021/dsa-4861	2023-11-07
https://access.redhat.com/security/cve/CVE-2021-26937	2022-03-28
https://bugzilla.redhat.com/show_bug.cgi?id=1927062	2022-03-28

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Gnu Search vendor "Gnu"		Screen Search vendor "Gnu" for product "Screen"				<= 4.8.0 Search vendor "Gnu" for product "Screen" and version " <= 4.8.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				9.0 Search vendor "Debian" for product "Debian Linux" and version "9.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				10.0 Search vendor "Debian" for product "Debian Linux" and version "10.0"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				32 Search vendor "Fedoraproject" for product "Fedora" and version "32"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				33 Search vendor "Fedoraproject" for product "Fedora" and version "33"		-		Affected