CVE-2021-26937

high-risk

Published 2021-02-09

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.

Do I need to act?

11.9% chance of exploitation in next 30 days

EPSS score — higher than 88% of all CVEs

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 9.8/10 Critical

NETWORK / LOW complexity

Affected Products (5)

Screen

Debian Linux

Fedora

Affected Vendors

Debian Gnu Fedoraproject

References (19)

Exploit http://www.openwall.com/lists/oss-security/2021/02/09/8

Product https://ftp.gnu.org/gnu/screen/

Mailing List https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...

Exploit https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html

Third Party Advisory https://security.gentoo.org/glsa/202105-11

Third Party Advisory https://www.debian.org/security/2021/dsa-4861

Exploit https://www.openwall.com/lists/oss-security/2021/02/09/3

Exploit http://www.openwall.com/lists/oss-security/2021/02/09/8

Product https://ftp.gnu.org/gnu/screen/

Mailing List https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...

Exploit https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html

Third Party Advisory https://security.gentoo.org/glsa/202105-11

https://security.netapp.com/advisory/ntap-20250509-0004/

Third Party Advisory https://www.debian.org/security/2021/dsa-4861

Exploit https://www.openwall.com/lists/oss-security/2021/02/09/3

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high-risk

Severity 32/34 · Critical

Exploitability 12/34 · Low

Exposure 12/34 · Low