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Fencer Vulns
high 7.5

CVE-2020-8184 json

Rack allows Percent-encoded cookies to overwrite existing prefixed cookie names

published 2020-06-19 6 y ago modified 2026-09-10 1 mo ago also GHSA-j6w9-fv6q-3q52 , EUVD-2020-0494

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.0%
EPSS 3.0% chance of exploitation in 30 days, percentile 87%
public exploits
0
none known

Summary

A reliance on cookies without validation/integrity check security vulnerability exists in rack < 2.2.3, rack < 2.1.4 that makes it is possible for an attacker to forge a secure or host-only cookie prefix.

Patch / fix

  • rubygems rack 2.1.4, 2.2.3
  • rack_project rack 2.1.4, 2.2.3
  • ruby-rack Debian 14, Debian 13, Debian 12 2.1.1-6

debian advisories DEBIAN-CVE-2020-8184

  • ruby-rack Ubuntu 16.04 LTS 1.6.4-3ubuntu0.2
  • ruby-rack Ubuntu 18.04 LTS 1.6.4-4ubuntu0.2
  • ruby-rack Ubuntu 20.04 LTS 2.0.7-2ubuntu0.1
  • ruby-rack Ubuntu Pro 14.04 LTS 1.5.2-3+deb8u3ubuntu1~esm4

ubuntu advisories UBUNTU-CVE-2020-8184

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • tfm satellite capsule 6.8, satellite 6.8 6.1-1.el7sat
  • kobo satellite capsule 6.8, satellite 6.8 0.5.1-1.el7sat
  • pulp satellite capsule 6.8, satellite 6.8 2.21.3-1.el7sat
  • gofer satellite capsule 6.8, satellite 6.8 2.12.5-7.el7sat
  • future satellite capsule 6.8, satellite 6.8 0.16.0-11.el7sat
  • ostree satellite capsule 6.8, satellite 6.8 2017.1-2.atomic.el7
  • foreman satellite capsule 6.8, satellite 6.8 2.1.2.19-1.el7sat
  • katello satellite capsule 6.8, satellite 6.8 3.16.0-1.el7sat

red hat advisories RHSA-2020:4366

  • rubygem-rack SLE High Availability Extension 15 SP4, SLE High Availability Extension 15 SP3, SLE High Availability Extension 15 SP2 +4 more 2.0.8-150000.3.9.1
  • rmt-server SLE Module for Server Applications 15 SP1, SLE Module for Public Cloud 15 SP1 2.6.5-3.18.1
  • rmt-server SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 2.6.5-3.34.1
  • rmt-server SLE Module for Server Applications 15 SP2, SLE Module for Public Cloud 15 SP2 2.6.5-3.3.1
  • rubygem-rack OpenStack Cloud Crowbar 9, OpenStack Cloud Crowbar 8, OpenStack Cloud 7 1.6.13-3.8.1
  • kibana OpenStack Cloud Crowbar 9, OpenStack Cloud 9 4.6.3-4.3.2
  • grafana OpenStack Cloud Crowbar 9, OpenStack Cloud 9 6.2.5-3.12.2
  • ansible1 OpenStack Cloud 9 1.9.6-9.7.2

suse advisories SUSE-SU-2022:3347-1SUSE-SU-2020:3160-1SUSE-SU-2020:3147-1SUSE-SU-2020:3036-1SUSE-SU-2020:2678-1SUSE-RU-2020:2161-1

  • rubygem-rack openSUSE Tumbleweed 3.1.18-1.3
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.22-1.1
  • rubygem-rack openSUSE Tumbleweed 3.1.12-1.1
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.11-1.1
  • rmt-server openSUSE Tumbleweed 2.6.13-1.1
  • rubygem-rack openSUSE Tumbleweed 2.2.3.1-1.1
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.4-1.1
  • ruby3.2-rubygem-rack-2.2 openSUSE Tumbleweed 2.2.7-1.1

opensuse advisories openSUSE-SU-2026:10358-1openSUSE-SU-2026:10286-1openSUSE-SU-2025:14875-1openSUSE-SU-2025:14811-1openSUSE-SU-2024:10589-1openSUSE-SU-2024:12119-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-8184 updated cvss 0.0

rubygem-rack: percent-encoded cookies can be used to overwrite existing prefixed cookie names

  • Red Hat CloudForms Management Engine 5 cfme-gemset, cfme-amazon-smartstate
    affected: no fix planned “Will not fix”
  • Red Hat OpenStack Platform 10 (Newton) Operational Tools rubygem-rack
    affected: no fix planned “Out of support scope”
  • Red Hat OpenStack Platform 13 (Queens) Operational Tools rubygem-rack
    affected: no fix available “Fix deferred”
  • Red Hat Satellite 6 tfm-ror52-rubygem-rack
    affected: no fix available
  • Red Hat Satellite 6.8 tfm 6.1-1.el7sat, kobo 0.5.1-1.el7sat, pulp 2.21.3-1.el7sat, gofer 2.12.5-7.el7sat, receptor 0.6.3-1.el7ar, future 0.16.0-11.el7sat, +488 more Red Hat Satellite Capsule 6.8 tfm 6.1-1.el7sat, kobo 0.5.1-1.el7sat, pulp 2.21.3-1.el7sat, gofer 2.12.5-7.el7sat, future 0.16.0-11.el7sat, katello 3.16.0-1.el7sat, +232 more
    fixed: vendor fix RHSA-2020:4366
  • Red Hat Enterprise Linux 9 rubygem-rack Red Hat Storage 3 rubygem-rack
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.01% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/895727 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
rubygems rack
<2.1.4
>=2.2.0, <2.2.3
2.1.4
2.2.3

Affected products

  • n/a https://github.com/rack/rack

Classification

Weakness
  • CWE-784 Reliance on Cookies without Validation and Integrity Checking in a Security Decision
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns 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.