Bug 2543974 (CVE-2026-103431)

Summary: CVE-2026-103431 collectl: collectl: colmux does not sanitize ANSI/VT100 terminal escape sequences in data received from remote collectl instances
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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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]).
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Description OSIDB Bzimport 2026-09-30 15:41:32 UTC 
A flaw was found in collectl's colmux utility. colmux receives monitoring data from remote collectl instances over TCP port 2655 and renders it directly to the operator's terminal without neutralizing ANSI/VT100 terminal escape sequences. An unprivileged local user on any host monitored by collectl can embed terminal escape sequences in their process name (argv[0], read from /proc), which collectl (commonly run as root via its systemd unit, which has no User= directive) forwards unmodified to colmux. When an operator views this data via colmux, the injected sequences are interpreted by their terminal emulator, reliably allowing screen clearing and spoofed on-screen content. Depending on the operator's terminal emulator configuration, this could conditionally extend to clipboard manipulation or, if the operator pastes unseen clipboard content into a shell, command execution. The issue was fixed upstream in collectl 4.3.20.2/4.3.20.3 by sanitizing remote data at ingestion in colmux and at the source in collectl's formatit.ph, gated by a default-on sanitizer with a --rawescape opt-out flag for trusted networks. Fedora has shipped the fix (collectl-4.3.20.3, FEDORA-2026-71a9784a57).