CVE-2026-103431

Description

colmux in collectl before 4.3.20.2 does not sanitize ANSI/VT100 terminal escape sequences in data received from remote collectl instances before displaying it, allowing a local user on a monitored host to inject escape sequences into the terminal of an operator running colmux, via a crafted process name (argv[0]).

Statement

This vulnerability is rated as having an Important impact because an unprivileged local user on a monitored host can cross security boundaries to compromise the terminal session of an administrative operator. In enterprise monitoring environments, the colmux aggregation tool consolidates process telemetry from distributed systems running collectl and displays it directly to administrative consoles. Because control characters from remote process names are processed without neutralization, this enables arbitrary screen manipulation and, depending on the operator's terminal configuration, potential command injection. Although exploitation requires active operator observation and specific terminal capabilities, the ability to facilitate remote privilege escalation across systems warrants the Important rating.

Mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Understanding the Weakness (CWE)

Integrity

Technical Impact: Execute Unauthorized Code or Commands; Hide Activities; Unexpected State

ANSI escape codes can be used for low-severity attacks such as changing the color of console output, but they can also be used to arbitrarily move the cursor, clear the screen, and make fake prompts inside the interactive CLI via malicious user input. In some contexts - depending on the functionality of the terminal in use - ANSI escape codes can be used to execute arbitrary code.

Acknowledgements

This issue was discovered by Laurence Oberman (Red Hat) and Nathan Scott (Red Hat).

Frequently Asked Questions

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