How severe is CVE-2021-21673?

CVE-2021-21673 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-21673 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21673?

CVE-2021-21673 affects Jenkins Cas. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21673?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-21673 published?

CVE-2021-21673 was published on 2021-06-30 and last updated on 2026-06-17.

CVE-2021-21673

CVE-2021-21673 is a medium-severity vulnerability in Jenkins Cas with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 5.8
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Jenkins Cas
Published: 2021-06-30
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-21673?: 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.
How severe is CVE-2021-21673?: CVE-2021-21673 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-21673 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21673?: CVE-2021-21673 affects Jenkins Cas. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21673?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-21673 published?: CVE-2021-21673 was published on 2021-06-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:jenkins:cas:*:*:*:*:*:jenkins:*:*

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