CVE-2026-93421
MediumCVSS 5.3Summary
Mesop is a Python-based UI framework for building web applications. Prior to 1.3.4, the unauthenticated /__csp__ endpoint passes attacker-controlled document-uri, blocked-uri, and violated-directive values to the csp_report handler in mesop/server/static_file_serving.py, which prints them to standard output without neutralizing terminal control sequences. When an operator views the resulting logs in an ANSI-capable terminal, injected ANSI or VT100 sequences can clear or reposition the display, hide text, or present forged messages, reducing the integrity of monitoring and incident-response output. This issue is fixed in version 1.3.4.
Risk Assessment
An attacker can inject malicious terminal sequences into logs, potentially leading to manipulation of displayed information, hiding of real events, or presentation of forged data. This affects the integrity of monitoring and incident-response processes.
Recommendation
Update Mesop to version 1.3.4 or later, which contains the fix for this vulnerability. If updating is not possible, consider restricting access to the /__csp__ endpoint or monitoring logs for unusual ANSI sequences.
Other vulnerabilities in Mesop
See all- CVE-2026-77357High
Mesop prior to version 1.3.3, when running in debug mode, exposes a GET /hot-reload endpoint whose unbounded loop depends on the user-supplied counter parameter. An unauthenticated attacker can send requests with high counter values, exhausting the worker pool and making the server unavailable. The attack requires minimal effort and leaves the server unresponsive until manually restarted.
- CVE-2026-34824High
Mesop, a Python-based UI framework, from version 1.2.3 to before version 1.2.5 contains an uncontrolled resource consumption vulnerability in the WebSocket implementation. An unauthenticated attacker can send a rapid succession of WebSocket messages, forcing the server to spawn an unbounded number of OS threads, leading to thread exhaustion and Out of Memory (OOM) errors, causing a complete Denial of Service (DoS).
Original NVD description (English source)
Mesop is a Python-based UI framework that allows users to build web applications. Prior to 1.3.4, the unauthenticated /__csp__ endpoint passes attacker-controlled document-uri, blocked-uri, and violated-directive values to the csp_report handler in mesop/server/static_file_serving.py, which prints them to standard output without neutralizing terminal control sequences. When an operator views the resulting logs in an ANSI-capable terminal, injected ANSI or VT100 sequences can clear or reposition the display, hide text, or present forged messages, reducing the integrity of monitoring and incident-response output. This issue is fixed in version 1.3.4.