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Mesop EUVDEUVD-2026-66114

| CVE-2026-77357 HIGH
Uncontrolled Resource Consumption (CWE-400)
2026-08-25 GitHub_M
Python Denial Of Service Mesop
8.7
CVSS 4.0 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
8.7 HIGH
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
7.5 HIGH

Network-reachable unauthenticated GET endpoint; no scope change as only the Mesop process is affected; pure availability impact from thread exhaustion with no data exposure.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

4
Patch available
Aug 25, 2026 - 22:04 EUVD
Source Code Evidence Fetched
Aug 25, 2026 - 21:21 vuln.today
Analysis Generated
Aug 25, 2026 - 21:21 vuln.today
CVE Published
Aug 25, 2026 - 20:40 cve.org
HIGH 8.7

DescriptionCVE.org

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.

AnalysisAI

Worker-thread exhaustion in Mesop's debug-mode hot-reload endpoint (prior to version 1.3.3) allows an unauthenticated remote attacker to render the server completely unavailable with minimal effort. The GET /hot-reload endpoint in debug mode enters an unbounded loop controlled by the attacker-supplied counter parameter, holding worker threads indefinitely until the thread pool is exhausted and the server stops responding to all requests. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Identify Mesop server running in debug mode
Delivery
Send concurrent GET /hot-reload?counter=<large_integer> requests
Exploit
Each request blocks a worker thread in unbounded loop
Execution
Exhaust server worker pool
Persist
Server unresponsive to all traffic
Impact
Manual restart required to recover
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Vulnerability AssessmentAI

Exploitation Exploitation strictly requires that the Mesop application is running with debug mode enabled - this is the sole non-default configuration that exposes the /hot-reload endpoint. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 vector AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N scoring 8.7 accurately reflects the attack characteristics: network-reachable, no complexity or privileges, fully automatable, with high availability impact and no confidentiality or integrity loss. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker discovers a Mesop application running in debug mode on a reachable HTTP port and sends repeated concurrent GET requests to /hot-reload?counter=999999999. Each request ties up a server worker thread in an infinite loop awaiting a counter increment that never arrives; after sending enough concurrent requests to fill the worker pool, the server becomes unresponsive to all legitimate traffic. …
Remediation Upgrade to Mesop version 1.3.3, which is the vendor-confirmed fixed release available at https://github.com/mesop-dev/mesop/releases/tag/v1.3.3. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours, immediately disable debug mode on all production Mesop instances and verify configuration change across all deployments. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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EUVD-2026-66114 vulnerability details – vuln.today
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