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CVE-2020-15166

20
FAUCET Score

CVE-2020-15166 is a denial-of-service vulnerability affecting ZeroMQ versions prior to 4.3.3, impacting users with public TCP endpoints, even when CURVE/ZAP security is enabled. An attacker can prevent legitimate clients from exchanging messages by connecting a raw TCP socket to a configured endpoint, leading to messages being delivered to the library but not the server application. Rated 7.5 HIGH (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), this vulnerability is easily exploitable over the network with low complexity, resulting in a complete loss of availability. There is no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.3.3CPE matchmatch criteria
cpe:2.3:a:zeromq:libzmq:*:*:*:*:*:*:*:*
32CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.41%
Probability of exploitation in next 30 days
EPSS Percentile
87.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0341 is in the 78th percentile among its peer group of 51,506 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2020-15166Moderate

zeromq: unauthenticated clients causing denial-of-service

Sep 7, 2020

References

github.com / zeromq/libzmq/pull/3913
PatchThird Party Advisory
github.com / zeromq/libzmq/pull/3973
PatchThird Party Advisory
github.com / zeromq/libzmq/security/advisories/GHSA-25wp-cf8g-938m
PatchThird Party Advisory
lists.debian.org / debian-lts-announce/2020/11/msg00017.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/BZ5IMNQXDB52JFBXHFLK4AHVORFELNNG
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/YFW2ZELCCPS4VLU4OSJOH5YL6KFKTFYW
security.gentoo.org / glsa/202009-12
Third Party Advisory