CVE-2021-21673
Open redirect vulnerability in Jenkins CAS Plugin
Jenkins CAS Plugin 1.6.0 and earlier improperly determines that a redirect URL after login is legitimately pointing to Jenkins, allowing attackers to perform phishing attacks.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
Jenkins CAS Plugin 1.6.0 and earlier improperly determines that a redirect URL after login is legitimately pointing to Jenkins, allowing attackers to perform phishing attacks.
- Record
CVE-2021-21673- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 5.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:N - Updated
- 2026-11-02
CVE List No score
Jenkins CAS Plugin 1.6.0 and earlier improperly determines that a redirect URL after login is legitimately pointing to Jenkins, allowing attackers to perform phishing attacks.
- Record
CVE-2021-21673- Updated
- 2026-11-02
EUVDEUVD-2022-2055 No score
Jenkins CAS Plugin 1.6.0 and earlier improperly determines that a redirect URL after login is legitimately pointing to Jenkins, allowing attackers to perform phishing attacks.
- Record
EUVD-2022-2055- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-2vvr-5757-qp87
Open redirect vulnerability in Jenkins CAS Plugin
Jenkins CAS Plugin 1.6.0 and earlier improperly determines that a redirect URL after login is legitimately pointing to Jenkins.
This allows attackers to perform phishing attacks by having users go to a Jenkins URL that will forward them to a different site after successful authentication.
Jenkins CAS Plugin 1.6.1 only redirects to relative (Jenkins) URLs.
- Record
GHSA-2vvr-5757-qp87- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
OSV
Jenkins CAS Plugin 1.6.0 and earlier improperly determines that a redirect URL after login is legitimately pointing to Jenkins, allowing attackers to perform phishing attacks.
- Record
CVE-2021-21673- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVGHSA-2vvr-5757-qp87
Open redirect vulnerability in Jenkins CAS Plugin
Jenkins CAS Plugin 1.6.0 and earlier improperly determines that a redirect URL after login is legitimately pointing to Jenkins.
This allows attackers to perform phishing attacks by having users go to a Jenkins URL that will forward them to a different site after successful authentication.
Jenkins CAS Plugin 1.6.1 only redirects to relative (Jenkins) URLs.
- Record
GHSA-2vvr-5757-qp87- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
org.jenkins-ci.plugins:cas-pluginMaven |
through 1.6.0 | 1.6.1 |
org.jenkins-ci.plugins:cas-pluginMaven |
before 1.6.1, plus listed versions 1.0.01.1.01.1.11.1.21.2.0 Show 7 moreShow less1.3.01.4.01.4.11.4.21.4.31.5.01.6.0 |
1.6.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21673 is a medium vulnerability (CVSS 6.1) in Jenkins Cas, published June 30, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.58%, the 75th percentile. Fixed in org.jenkins-ci.plugins:cas-plugin 1.6.1.