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Ubuntu 22.04 7978-1 GNU Screen Important Local Attack Risks

ubuntu
Calendar Grey January 26, 2026
Dist Ubuntu Esm H88
Multiple security issues fixed in GNU Screen for Ubuntu 22.04 and 24.04 LTS, addressing denial of service risks and unauthorized access.
Several security issues were fixed in GNU Screen.

Summary

Several security issues were fixed in GNU Screen.

Software Description:

- screen: terminal multiplexer with VT100/ANSI terminal emulation

Details:

It was discovered that GNU Screen incorrectly handled signals when setuid

or setgid privileges were being used, which is not the default in Ubuntu.

A local attacker could use this issue to send privileged signals, possibly

leading to a denial of service. This issue only affected Ubuntu 22.04 LTS.

(CVE-2023-24626)

It was discovered that GNU Screen incorrectly handled PTY permissions. A

local attacker could possibly use this issue to connect to an unauthorized

screen session. (CVE-2025-46802)

It was discovered that GNU Screen incorrectly handled file access when

setuid privileges were being used, which is not the default in Ubuntu. A

local attacker could use this issue to deduce information about certain

file paths. (CVE-2025-46804)

It was discovered that GNU Screen incorrectly handled signals when setuid

privileges were being used, ...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory denial of service Ubuntu important screen local attack

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 24.04 LTS
  screen                          4.9.1-1ubuntu1

Ubuntu 22.04 LTS
  screen                          4.9.0-1ubuntu0.1

In general, a standard system update will make all the necessary changes.

References

https://ubuntu.com/security/notices/USN-7978-1

CVE-2023-24626, CVE-2025-46802, CVE-2025-46804, CVE-2025-46805

Severity
important
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-7978-1

Topics%20covered

Topics Covered

security advisory denial of service Ubuntu important screen local attack

Package Information

https://launchpad.net/ubuntu/+source/screen/4.9.1-1ubuntu1
https://launchpad.net/ubuntu/+source/screen/4.9.0-1ubuntu0.1

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