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Fencer Intel
high 8.5

CVE-2020-11020 json

Authentication and extension bypass in Faye

published 6y ago modified last mo. also GHSA-qpg4-4w7w-2mq5 , EUVD-2020-0392

cvss
8.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

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.

Patch / fix

  • rubygems faye 1.0.4, 1.1.3, 1.2.5
  • faye_project faye 1.0.4, 1.1.3, 1.2.5
  • ruby-faye Debian 12 1.4.0-1

debian advisories DEBIAN-CVE-2020-11020

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Exploit prediction

1.57% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/faye/faye/security/advisories/GHSA-qpg4-4w7w-2mq5 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.1 8.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
rubygems faye
>=0.5.0, <1.0.4
>=1.1.0, <1.1.3
>=1.2.0, <1.2.5
1.0.4
1.1.3
1.2.5

Affected products

  • faye Faye

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.