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

Unknown severity · Source severity not reportedCVE-2026-77357

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

Answer in brief

CVE-2026-77357 records a Unknown severity vulnerability in Mesop: DoS in /hot-reload endpoint allows unauthenticated attacker to exhaust worker threads and crash the server. The current sources do not mark it as known exploited. The current feed maps mesop-dev/mesop (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 25, 2026Updated Aug 25, 2026Source checked Aug 25, 2026First seen by HOL Aug 25, 2026Material review Aug 25, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps mesop-dev/mesop (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
mesop-dev/mesopgeneric	< 1.3.3	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for mesop-dev/mesop.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 25, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.