CVE-2020-15134: Faye before version 1.4.0, there is a lack of certification validation in TLS handshakes

Q: How do I fix CVE-2020-15134?

faye: upgrade to 1.4.0. Exact commands for each OS are on this page.

Q: Is CVE-2020-15134 being exploited?

CVE-2020-15134 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-15134 affect?

CVE-2020-15134 affects faye. Severity is high (CVSS 8.0). Faye before version 1.4.0, there is a lack of certification validation in TLS handshakes. Faye uses em-http-request and faye-websocket in the Ruby version of its client. Those libraries both use the `EM::Connection#start_tls` method in Even

Q: How urgent is CVE-2020-15134?

Priority 48/100. High severity; Public exploit reference

This month

HIGH 8.0UPGRADE

CVE-2020-15134 is a high-severity flaw (CVSS 8.0) affecting faye. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Faye before version 1.4.0, there is a lack of certification validation in TLS handshakes. Faye uses em-http-request and faye-websocket in the Ruby version of its client. Those libraries both use the `EM::Connection#start_tls` method in EventMachine to implement the TLS handshake whenever a `wss:` URL is used for the connection. This method does not implement certificate verification by default, meaning that it does not check that the server prese

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.0 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-295
Published	2020-07-31
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: faye project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-07-31 18:15 UTCPublished CVE record published
2026-06-17 02:56 UTCUpdated Record last modified

faye project faye UPGRADE

Affected: < 1.4.0

Fixed in: 1.4.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy faye || rpm -q faye || faye --version

2. UPGRADE to 1.4.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade faye

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade faye

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-15134?

faye: upgrade to 1.4.0. Exact commands for each OS are on this page.

Is CVE-2020-15134 being exploited?

CVE-2020-15134 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-15134 affect?

CVE-2020-15134 affects faye. Severity is high (CVSS 8.0). Faye before version 1.4.0, there is a lack of certification validation in TLS handshakes. Faye uses em-http-request and faye-websocket in the Ruby version of its client. Those libraries both use the `EM::Connection#start_tls` method in Even

How urgent is CVE-2020-15134?

Priority 48/100. High severity; Public exploit reference

Software pages

Ruby vulnerabilities

Related CVEs

CVE-2020-11020 HIGH 8.5 UPGRADE UPGRADE Faye (NPM, RubyGem) versions greater than 0.5.0 and before 1.0.4, 1.1.3 and 1.2.5, has the potential for authe

References

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