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Fencer Intel
critical 10.0

CVE-2020-5415 json

Concourse's GitLab auth allows impersonation

published 6y ago modified 2mo ago also BIT-concourse-2020-5415 , EUVD-2021-2453 , GHSA-627p-rr78-99rj

cvss
10.0
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
0
none known

Summary

Concourse, versions prior to 6.3.1 and 6.4.1, in installations which use the GitLab auth connector, is vulnerable to identity spoofing by way of configuring a GitLab account with the same full name as another user who is granted access to a Concourse team. GitLab groups do not have this vulnerability, so GitLab users may be moved into groups which are then configured in the Concourse team.

Patch / fix

  • go github.com/concourse/concourse 0.0.0-20200730151558-b00d1c8d8576, 1.6.1-0.20200730151558-b00d1c8d8576, 6.3.1, 6.4.1
  • go github.com/concourse/dex 0.0.0-20200730150203-821b48abfd88, 6.3.1, 6.4.1
  • bitnami concourse 6.3.1, 6.4.1
  • VMware Tanzu Concourse 6.3.1, 6.4.1

Is CVE-2020-5415 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

1.22% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.0 10.0 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:P/A:N
OSV 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
go github.com/concourse/concourse
>=6.4.0, <6.4.1
>=1.6.1, <6.3.1
<0.0.0-20200730151558-b00d1c8d8576
>=0.0.0, <1.6.1-0.20200730151558-b00d1c8d8576
6.4.1
6.3.1
0.0.0-20200730151558-b00d1c8d8576
1.6.1-0.20200730151558-b00d1c8d8576
go github.com/concourse/dex
>=6.4.0, <6.4.1
>=0.0.0, <6.3.1
<0.0.0-20200730150203-821b48abfd88
6.4.1
6.3.1
0.0.0-20200730150203-821b48abfd88
bitnami concourse
<6.3.1
>=6.4.0, <6.4.1
6.3.1
6.4.1

Affected products

  • VMware Tanzu Concourse

Classification

Weakness
  • CWE-290 Authentication Bypass by Spoofing

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.