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9.8
CRITICAL CVSS 3.1
CVE-2021-26937
GNU Screen UTF-8 Encoding Denial of Service
Description

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.

INFO

Published Date :

Feb. 9, 2021, 8:15 p.m.

Last Modified :

May 9, 2025, 8:15 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Affected Products

The following products are affected by CVE-2021-26937 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Fedoraproject fedora
1 Debian debian_linux
1 Gnu screen
: Total Affected Vendor : 3 | Products : 3
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 2.0 HIGH [email protected]
CVSS 3.1 CRITICAL [email protected]
Solution
This vulnerability is addressed by updating the GNU screen package.
  • Update the screen packages to the latest available version.
  • If applicable, upgrade Prism Central before upgrading.
Public PoC/Exploit Available at Github

CVE-2021-26937 has a 1 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-26937.

URL Resource
http://www.openwall.com/lists/oss-security/2021/02/09/8 Exploit Mailing List Third Party Advisory
https://ftp.gnu.org/gnu/screen/ Product
https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM/
https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html Exploit Mailing List Vendor Advisory
https://security.gentoo.org/glsa/202105-11 Third Party Advisory
https://www.debian.org/security/2021/dsa-4861 Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/02/09/3 Exploit Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/02/09/8 Exploit Mailing List Third Party Advisory
https://ftp.gnu.org/gnu/screen/ Product
https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM/
https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html Exploit Mailing List Vendor Advisory
https://security.gentoo.org/glsa/202105-11 Third Party Advisory
https://security.netapp.com/advisory/ntap-20250509-0004/
https://www.debian.org/security/2021/dsa-4861 Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/02/09/3 Exploit Mailing List Third Party Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-26937 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-26937 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Profile Photo
Morton-Li/BoltWrt

BoltWrt是一款嵌入式路由器系统,它在OpenWrt的基础上,针对中国的用户需求和网络环境,添加了很多高级功能和特性.它的目标是打造一个高效,稳定,安全,易用的路由器系统.

openwrt

Makefile Awk Shell C Assembly C++ M4 CMake Perl Lex

Updated: 8 months, 1 week ago
40 stars 8 fork 8 watcher
Born at : Jan. 22, 2021, 4:43 a.m. This repo has been linked 5 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-26937 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2021-26937 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    May. 09, 2025

    Action Type Old Value New Value
    Added Reference https://security.netapp.com/advisory/ntap-20250509-0004/
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference http://www.openwall.com/lists/oss-security/2021/02/09/8
    Added Reference https://ftp.gnu.org/gnu/screen/
    Added Reference https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html
    Added Reference https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL/
    Added Reference https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM/
    Added Reference https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html
    Added Reference https://security.gentoo.org/glsa/202105-11
    Added Reference https://www.debian.org/security/2021/dsa-4861
    Added Reference https://www.openwall.com/lists/oss-security/2021/02/09/3
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    Nov. 07, 2023

    Action Type Old Value New Value
    Added Reference MITRE https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM/ [No types assigned]
    Added Reference MITRE https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL/ [No types assigned]
    Removed Reference MITRE https://lists.fedoraproject.org/archives/list/[email protected]/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM/
    Removed Reference MITRE https://lists.fedoraproject.org/archives/list/[email protected]/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL/
  • Modified Analysis by [email protected]

    May. 06, 2022

    Action Type Old Value New Value
    Changed Reference Type https://security.gentoo.org/glsa/202105-11 No Types Assigned https://security.gentoo.org/glsa/202105-11 Third Party Advisory
  • CVE Modified by [email protected]

    May. 26, 2021

    Action Type Old Value New Value
    Added Reference https://security.gentoo.org/glsa/202105-11 [No Types Assigned]
  • Modified Analysis by [email protected]

    Mar. 15, 2021

    Action Type Old Value New Value
    Changed Reference Type https://lists.fedoraproject.org/archives/list/[email protected]/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL/ No Types Assigned https://lists.fedoraproject.org/archives/list/[email protected]/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL/ Mailing List, Third Party Advisory
    Changed Reference Type https://lists.fedoraproject.org/archives/list/[email protected]/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM/ No Types Assigned https://lists.fedoraproject.org/archives/list/[email protected]/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM/ Mailing List, Third Party Advisory
    Added CPE Configuration OR *cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* *cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
  • CVE Modified by [email protected]

    Mar. 04, 2021

    Action Type Old Value New Value
    Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/GNWBOIDEPOEQS5RMQVMFKHKXJCGNYWBL/ [No Types Assigned]
  • CVE Modified by [email protected]

    Mar. 04, 2021

    Action Type Old Value New Value
    Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/JJWLXP45POUUYBJRRWPVAWNZDJTLYWVM/ [No Types Assigned]
  • Modified Analysis by [email protected]

    Feb. 24, 2021

    Action Type Old Value New Value
    Changed Reference Type http://www.openwall.com/lists/oss-security/2021/02/09/8 Exploit, Third Party Advisory http://www.openwall.com/lists/oss-security/2021/02/09/8 Exploit, Mailing List, Third Party Advisory
    Changed Reference Type https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html No Types Assigned https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html Mailing List, Third Party Advisory
    Changed Reference Type https://www.debian.org/security/2021/dsa-4861 No Types Assigned https://www.debian.org/security/2021/dsa-4861 Third Party Advisory
    Added CPE Configuration OR *cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* *cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
  • CVE Modified by [email protected]

    Feb. 22, 2021

    Action Type Old Value New Value
    Added Reference https://www.debian.org/security/2021/dsa-4861 [No Types Assigned]
  • CVE Modified by [email protected]

    Feb. 19, 2021

    Action Type Old Value New Value
    Added Reference https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html [No Types Assigned]
  • Initial Analysis by [email protected]

    Feb. 17, 2021

    Action Type Old Value New Value
    Added CVSS V2 NIST (AV:N/AC:L/Au:N/C:P/I:P/A:P)
    Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    Changed Reference Type http://www.openwall.com/lists/oss-security/2021/02/09/8 No Types Assigned http://www.openwall.com/lists/oss-security/2021/02/09/8 Exploit, Third Party Advisory
    Changed Reference Type https://ftp.gnu.org/gnu/screen/ No Types Assigned https://ftp.gnu.org/gnu/screen/ Product
    Changed Reference Type https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html No Types Assigned https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html Exploit, Mailing List, Vendor Advisory
    Changed Reference Type https://www.openwall.com/lists/oss-security/2021/02/09/3 No Types Assigned https://www.openwall.com/lists/oss-security/2021/02/09/3 Exploit, Mailing List, Third Party Advisory
    Added CWE NIST CWE-88
    Added CPE Configuration OR *cpe:2.3:a:gnu:screen:*:*:*:*:*:*:*:* versions up to (including) 4.8.0
  • CVE Modified by [email protected]

    Feb. 10, 2021

    Action Type Old Value New Value
    Added Reference http://www.openwall.com/lists/oss-security/2021/02/09/8 [No Types Assigned]
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 9.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact
Base CVSS Score: 7.5
Access Vector
Access Complexity
Authentication
Confidentiality Impact
Integrity Impact
Availability Impact
Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

2.98 }} 1.54%

score

0.85936

percentile