CVE-2020-15166

Name: CVE-2020-15166
Creator: NVD / NIST
Published: 2020-09-11T16:15:12.177+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 3.41%

Last modified Jun 17, 2026

CVE-2020-15166 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 3.41% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

3.41%

87.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-400

Affected Software

Vendor	Product	Versions
Zeromq	Libzmq	< 4.3.3
Fedoraproject	Fedora	32
Fedoraproject	Fedora	33
Debian	Debian Linux	9.0

References

https://github.com/zeromq/libzmq/pull/3913Patch, Third Party Advisory
https://github.com/zeromq/libzmq/pull/3973Patch, Third Party Advisory
https://github.com/zeromq/libzmq/security/advisories/GHSA-25wp-cf8g-938mPatch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/11/msg00017.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZ5IMNQXDB52JFBXHFLK4AHVORFELNNG/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YFW2ZELCCPS4VLU4OSJOH5YL6KFKTFYW/
https://security.gentoo.org/glsa/202009-12Third Party Advisory
https://github.com/zeromq/libzmq/pull/3913Patch, Third Party Advisory
https://github.com/zeromq/libzmq/pull/3973Patch, Third Party Advisory
https://github.com/zeromq/libzmq/security/advisories/GHSA-25wp-cf8g-938mPatch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/11/msg00017.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BZ5IMNQXDB52JFBXHFLK4AHVORFELNNG/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YFW2ZELCCPS4VLU4OSJOH5YL6KFKTFYW/
https://security.gentoo.org/glsa/202009-12Third Party Advisory

Timeline

Published: Sep 11, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-15166?

How severe is CVE-2020-15166?

CVE-2020-15166 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 3.41% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15166?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-15166?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST