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OpenAdvisories
High · 7.5 CVE-2026-34824 EUVD-2026-18909GHSA-3jr7-6hqp-x679PYSEC-2026-2204

Mesop: Unbounded Thread Creation in WebSocket Handler Leads to Denial of Service

Published Apr 3, 2026 · Updated Apr 6, 2026 · Assigned by GitHub_M

Description

Mesop is a Python-based UI framework that allows users to build web applications. From version 1.2.3 to before version 1.2.5, an uncontrolled resource consumption vulnerability exists in the WebSocket implementation of the Mesop framework. An unauthenticated attacker can send a rapid succession of WebSocket messages, forcing the server to spawn an unbounded number of operating system threads. This leads to thread exhaustion and Out of Memory (OOM) errors, causing a complete Denial of Service (DoS) for any application built on the framework. This issue has been patched in version 1.2.5.

Affected products

VendorProductAffectedFixed
mesop-dev mesop >= 1.2.3, < 1.2.5 —

Affected packages

EcosystemPackageAffectedFixedRecord
PyPI mesop >= 1.2.3, < 1.2.5 1.2.5 GHSA-3jr7-6hqp-x679

References