# CVE-2020-15166: libzmq5: In ZeroMQ before version 4.3.3, there is a denial-of-service vulnerability

CVE-2020-15166 is fixed in libzmq5 on 1 platform, first by libzmq5 4.2.5-1ubuntu0.2+esm1, released September 11, 2020. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2020-15166
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.0332
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 11, 2020

## Description

In ZeroMQ before version 4.3.3, there is a denial-of-service vulnerability. Users with TCP transport public endpoints, even with CURVE/ZAP enabled, are impacted. If a raw TCP socket is opened and connected to an endpoint that is fully configured with CURVE/ZAP, legitimate clients will not be able to exchange any message. Handshakes complete successfully, and messages are delivered to the library, but the server application never receives them. This is patched in version 4.3.3.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libzmq5 Ubuntu 18.04.6 LTS (bionic) | 4.2.5-1ubuntu0.2+esm1 | [libzmq5 4.2.5-1ubuntu0.2+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libzmq5-4.2.5-1ubuntu0.2-esm1.md) | Sep 11, 2020 |
| Linux | libzmq5 Ubuntu 20.04 LTS (focal) | 4.3.2-2ubuntu1.20.04.1~esm1 | [libzmq5 4.3.2-2ubuntu1.20.04.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libzmq5-4.3.2-2ubuntu1.20.04.1-esm1.md) | Sep 11, 2020 |

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