CVE-2026-77357

HighCVSS 8.7

Published: 25/08/2026(UTC)Updated: 26/08/2026(UTC)Translated: 26/08/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.30%

23th percentile - higher than 23% of all known CVEs

Summary

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.

Risk Assessment

A single attacker can cause complete unavailability of the Mesop server, disrupting web applications built with this framework.

Recommendation

Upgrade Mesop to version 1.3.3 or later, which includes a fix limiting the loop in the hot-reload endpoint.

Other vulnerabilities in Mesop

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 1.3.3, applications running in debug mode expose a GET /hot-reload endpoint whose unbounded loop depends on the user-supplied counter parameter, allowing an unauthenticated attacker to hold worker threads with high counter values until the worker pool is exhausted and the server becomes unavailable. A single unauthenticated attacker can crash the Mesop server with minimal effort. Because the attack leverages worker exhaustion, the server remains unresponsive until it is manually restarted. This issue is fixed in version 1.3.3.