CVE-2020-5409: Pivotal Concourse, most versions prior to 6.0.0, allows redirects to untrusted websites in its login flow

Routine

MEDIUM 6.1UPGRADE

CVE-2020-5409 is a medium-severity flaw (CVSS 6.1) affecting concourse. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Pivotal Concourse, most versions prior to 6.0.0, allows redirects to untrusted websites in its login flow. A remote unauthenticated attacker could convince a user to click on a link using the OAuth redirect link with an untrusted website and gain access to that user's access token in Concourse. (This issue is similar to, but distinct from, CVE-2018-15798.)

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-601
Published	2020-05-14
Last modified	2026-06-17

Publisher (CNA): Pivotal Software, Inc. · Vendor: pivotal software

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-05-14 00:15 UTCPublished CVE record published
2026-06-17 03:21 UTCUpdated Record last modified

pivotal software concourse UPGRADE

Affected: < 5.2.8 · >= 5.3.0 and < 5.5.10 · >= 5.6.0 and < 5.8.1

Fixed in: 5.2.8, 5.5.10, 5.8.1

Safe to downgrade to: a release before 5.3.0

1. Check installed version

apt-cache policy concourse || rpm -q concourse || concourse --version

2. UPGRADE to 5.2.8 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade concourse

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade concourse

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 5.3.0 (Debian / Ubuntu)

apt-cache madison concourse sudo apt install concourse=<VERSION_BEFORE_5.3.0> sudo apt-mark hold concourse

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list concourse sudo dnf downgrade concourse-<VERSION_BEFORE_5.3.0> sudo dnf versionlock add concourse

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-5409?

concourse: upgrade to 5.2.8, 5.5.10, 5.8.1. Exact commands for each OS are on this page.

Is CVE-2020-5409 being exploited?

CVE-2020-5409 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-5409 affect?

CVE-2020-5409 affects concourse. Severity is medium (CVSS 6.1). Pivotal Concourse, most versions prior to 6.0.0, allows redirects to untrusted websites in its login flow. A remote unauthenticated attacker could convince a user to click on a link using the OAuth redirect link with an untrusted website an

How urgent is CVE-2020-5409?

Priority 36/100. No elevated risk signals yet.

Related CVEs

CVE-2022-31683 MEDIUM 5.4 UPGRADE Concourse (7.x.y prior to 7.8.3 and 6.x.y prior to 6.7.9) contains an authorization bypass issue
CVE-2020-5415 CRITICAL 10.0 UPGRADE Concourse, versions prior to 6.3.1 and 6.4.1, in installations which use the GitLab auth connector, is vulnera

References

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