python-engineio has unbound thread allocation that can cause denial of service
Impact
An attacker can cause the creation of unnecessary background threads in the python-engineio server by exploiting the heartbeat mechanism, which launches a thread when a new connection is received, and when the client sends a PONG packet.
Note: this issue primarily affects synchronous servers. Asynchronous servers allocate background tasks instead of physical threads, which are lightweight and less likely to cause denial of service. However, the fix that was implemented was also applied to the asynchronous case.
Patches
Version 4.13.2 addresses this issue as follows:
- The initial background thread (or async task( for heartbeat management is only launched if a client passes authentication in the
connecthandler. - The server now ensures that there is only one background heatbeat thread (or async task) per client at a given point in time. Out of sequence PONG packets are now discarded when an active heartbeat thread is already running.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Python (PyPI) | python-engineio | < 4.13.2 | 4.13.2 |
Referencias
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Debilidad (CWE)
CWE-770- Plataforma
- Python (PyPI)
- Paquete
python-engineio- Publicada
- 26.06.2026
- Actualizado
- 11.10.2026 14:17
Fuentes y licencias
OSV / GitHub Advisory Database - PYSEC-2026-3032 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-cgwc-pv48-fhj5 - CC BY 4.0
Historial de vulnerabilidades: python-engineio
Todas las vulnerabilidades publicadas de este paquete (Python (PyPI)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 3
- Primera → última
- 07.2019 06.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 3
Divulgaciones por año
- 2019: 1
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 2
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python-engineio has unbound thread allocation that can cause denial of service esta entrada
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