CVE-2021-26937

Name: CVE-2021-26937
Creator: NVD / NIST
Published: 2021-02-09T20:15:14.91+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 9.15%

Last modified Jun 17, 2026

CVE-2021-26937 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 9.15% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

9.15%

94.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-88

Affected Software

Vendor	Product	Versions
Gnu	Screen	<= 4.8.0
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Fedoraproject	Fedora	32
Fedoraproject	Fedora	33

References

http://www.openwall.com/lists/oss-security/2021/02/09/8Exploit, Mailing List, Third Party Advisory
https://ftp.gnu.org/gnu/screen/Product
https://lists.debian.org/debian-lts-announce/2021/02/msg00031.htmlMailing 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.htmlExploit, Mailing List, Vendor Advisory
https://security.gentoo.org/glsa/202105-11Third Party Advisory
https://www.debian.org/security/2021/dsa-4861Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/02/09/3Exploit, Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/02/09/8Exploit, Mailing List, Third Party Advisory
https://ftp.gnu.org/gnu/screen/Product
https://lists.debian.org/debian-lts-announce/2021/02/msg00031.htmlMailing 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.htmlExploit, Mailing List, Vendor Advisory
https://security.gentoo.org/glsa/202105-11Third Party Advisory
https://security.netapp.com/advisory/ntap-20250509-0004/
https://www.debian.org/security/2021/dsa-4861Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/02/09/3Exploit, Mailing List, Third Party Advisory

Timeline

Published: Feb 9, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-26937?

How severe is CVE-2021-26937?

CVE-2021-26937 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 9.15% probability of exploitation in the next 30 days.

How do I fix CVE-2021-26937?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-26937?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST