Vulnerability · Published Aug 25, 2026 · Assigned by GitHub_M

CVE-2026-77357Mesop: DoS in /hot-reload endpoint allows unauthenticated attacker to exhaust worker threads and crash the server

High 8.7

In plain English

A high-severity uncontrolled resource consumption in mesop from mesop-dev. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities).

Severity (CVSS 4.0)8.7High

Exploit odds (30 days)0.5%top 55.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
mesop-dev	mesop	< 1.3.3

Weakness: CWE-400, CWE-834 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

https://github.com/mesop-dev/mesop/security/advisories/GHSA-8p72-497j-83mx x_refsource_CONFIRM
https://github.com/mesop-dev/mesop/commit/2b8e7f2c349c9e2eec202f46b07bada83061ce2d x_refsource_MISC
https://github.com/mesop-dev/mesop/releases/tag/v1.3.3 x_refsource_MISC