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Fencer Intel
high 8.8

CVE-2018-20321 json

Access Control Bypass

published 7y ago modified 4mo ago also GHSA-9qq2-xhmc-h9qr , GO-2022-0644 , EUVD-2021-1305

cvss
8.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

An issue was discovered in Rancher 2 through 2.1.5. Any project member with access to the default namespace can mount the netes-default service account in a pod, and then use that pod to execute administrative privileged commands against the k8s cluster. This could be mitigated by isolating the default namespace in a separate project, where only cluster admins can be given permissions to access. As of 2018-12-20, this bug affected ALL clusters created or imported by Rancher.

Patch / fix

  • go github.com/rancher/rancher 2.1.6, 2.1.6+incompatible

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Exploit prediction

1.77% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 8.8 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 9.0 AV:N/AC:L/Au:S/C:C/I:C/A:C
GitHub 3.1 4.2 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/rancher/rancher
>=2.0.0, <2.1.6
>=2.0.0+incompatible, <2.1.6+incompatible
2.1.6
2.1.6+incompatible

Classification

Weakness
  • CWE-668 Exposure of Resource to Wrong Sphere
  • CWE-288 Authentication Bypass Using an Alternate Path or Channel

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.