USN-7978-1: GNU Screen vulnerabilities

Publication date

26 January 2026

Overview

Several security issues were fixed in GNU Screen.


Packages

  • 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...

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, 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. (CVE-2025-46805)


Update instructions

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

Learn more about how to get the fixes.

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

Ubuntu Release Package Version
24.04 LTS noble screen –  4.9.1-1ubuntu1
22.04 LTS jammy screen –  4.9.0-1ubuntu0.1

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