# CVE-2026-48802: python-engineio: python-engineio is a Python implementation of the Engine.IO realtime client and server

CVE-2026-48802 is fixed in 2 products on 1 platform, first by OPENSUSE-SU-2026:21182-1, released June 30, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-48802
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0058
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 30, 2026

## Description

python-engineio is a Python implementation of the Engine.IO realtime client and server. Prior to version 4.13.2, 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. 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. 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 `connect` handler; and 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python-engineio Debian 14 | 4.14.0-1 | [DEBIAN-CVE-2026-48802](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48802.md) | Aug 11, 2026 |
| Linux | python-python-engineio opensuse-leap 16.0 | 4.12.0-bp160.2.1 | [OPENSUSE-SU-2026:21182-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21182-1.md) | Jun 30, 2026 |
| Linux | python-python-engineio sles 15.6 | 4.3.4-150600.3.3.1 | [SUSE-SU-2026:3085-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-3085-1.md) | Jul 16, 2026 |
| Linux | python-python-engineio sles 15.7 | 4.3.4-150600.3.3.1 | [SUSE-SU-2026:3085-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-3085-1.md) | Jul 16, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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