Screen has a TOCTOU race potentially allowing to send SIGHUP, SIGCONT to privileged processes when installed setuid-root
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Source | ID | Title |
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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 |
USN-7978-1 | GNU Screen vulnerabilities |
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.176% probability within 30 days)
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ssvc
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| 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 By this time, the previously checked PID could have been replaced by a different, privileged process.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 |
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| Metrics |
cvssV4_0
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| Type | Values Removed | Values Added |
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| 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 | |
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| Metrics |
threat_severity
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cvssV3_1
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