CVE-2020-11020: Authentication and extension bypass in Faye

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-04-29 · updated 2026-06-17
Weakness: CWE-287

Description

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 authentication bypass in the extension system. The vulnerability allows any client to bypass checks put in place by server-side extensions, by appending extra segments to the message channel. It is patched in versions 1.0.4, 1.1.3 and 1.2.5.

Affected products

Faye: from 0.5.0 (excl.) before 1.0.4; from 1.1.0 before 1.1.3; from 1.2.0 before 1.2.5 — fixed in 1.0.4, 1.1.3, 1.2.5

How to fix

Upgrade to a fixed version: Faye 1.0.4, 1.1.3, 1.2.5. Check the vendor advisory for mitigations.

References

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