CVE-2025-46805

Screen has a TOCTOU race potentially allowing to send SIGHUP, SIGCONT to privileged processes when installed setuid-root

Published May 26, 2025 CVSS 4.0 · 5.7 Medium EPSS < 1% KEV · Not listed
Description
Screen version 5.0.0 and older version 4 releases have a TOCTOU race potentially allowing to send SIGHUP, SIGCONT to privileged processes when installed setuid-root.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-28070 Screen version 5.0.0 and older version 4 releases have a TOCTOU race potentially allowing to send SIGHUP, SIGCONT to privileged processes when installed setuid-root.
Ubuntu USN Ubuntu USN USN-7978-1 GNU Screen vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A flaw was found in Screen. A possible denial of service caused by race conditions when sending signals exists. The `CheckPid()` function drops privileges to the real user ID and tests whether the kernel can send a signal to the target PID using these credentials. The signal is sent later via `Kill()`, potentially using full root privileges. By this time, the previously checked PID could have been replaced by a different, privileged process. It might also be possible to trick the privileged Screen daemon process into sending signals to itself since a process is always allowed to send signals to itself. Screen version 5.0.0 and older version 4 releases have a TOCTOU race potentially allowing to send SIGHUP, SIGCONT to privileged processes when installed setuid-root.
Title screen: Race Conditions when Sending Signals Screen has a TOCTOU race potentially allowing to send SIGHUP, SIGCONT to privileged processes when installed setuid-root
Weaknesses CWE-367
References
Metrics cvssV4_0

{'score': 5.7, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Type Values Removed Values Added
Description A flaw was found in Screen. A possible denial of service caused by race conditions when sending signals exists. The `CheckPid()` function drops privileges to the real user ID and tests whether the kernel can send a signal to the target PID using these credentials. The signal is sent later via `Kill()`, potentially using full root privileges. By this time, the previously checked PID could have been replaced by a different, privileged process. It might also be possible to trick the privileged Screen daemon process into sending signals to itself since a process is always allowed to send signals to itself.
Title screen: Race Conditions when Sending Signals
Weaknesses CWE-362
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Subscriptions

No data.

Weaknesses

Sources

Status
PUBLISHED
Assigner
suse
Published
Updated
May 27, 2025, 2:10 PM
Reserved
Apr 30, 2025, 11:28 AM
Status
Deferred
Published
May 26, 2025, 2:15 PM
Modified
Jun 17, 2026, 9:26 AM
Severity
Moderate
Public date
May 12, 2025, 12:00 AM