CVE-2020-5415 | Concourse's GitLab auth allows impersonation

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.

Published: 2020-08-12 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-5415 is rated Moderate Risk (63.6/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.22%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-5415

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.26% 1.22% +0.96%
2 2025-03-30 0.50% 0.26% -0.24%
3 2025-03-29 — 0.50% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-5415

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
10.0 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 5.8 [email protected]
10.0 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 6.0 [email protected]
6.4 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 4.9 [email protected]

Weakness enumeration for CVE-2020-5415

GitHub Security Advisory for CVE-2020-5415

GHSA-627p-rr78-99rj · Severity: high · Ecosystem: go — GitLab auth uses full name instead of username as user ID, allowing impersonation

Affected software / configurations for CVE-2020-5415

Vendor Product Version Raw CPE
pivotal_software concourse < 6.3.1 cpe:2.3:a:pivotal_software:concourse:*:*:*:*:*:*:*:*
pivotal_software concourse >= 6.4.0, < 6.4.1 cpe:2.3:a:pivotal_software:concourse:*:*:*:*:*:*:*:*

References for CVE-2020-5415

cvelogic Threat Intelligence