How severe is CVE-2021-21671?

CVE-2021-21671 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21671 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21671?

CVE-2021-21671 primarily affects Jenkins. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-21671?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-21671 published?

CVE-2021-21671 was published on 2021-06-30 and last updated on 2026-06-17.

CVE-2021-21671

CVE-2021-21671 is a high-severity vulnerability in Jenkins with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.1
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Jenkins
Published: 2021-06-30
Last modified: 2026-06-17

Description

Jenkins 2.299 and earlier, LTS 2.289.1 and earlier does not invalidate the previous session on login.

Frequently asked questions

What is CVE-2021-21671?: Jenkins 2.299 and earlier, LTS 2.289.1 and earlier does not invalidate the previous session on login.
How severe is CVE-2021-21671?: CVE-2021-21671 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21671 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21671?: CVE-2021-21671 primarily affects Jenkins. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-21671?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-21671 published?: CVE-2021-21671 was published on 2021-06-30 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:jenkins:jenkins:*:*:*:*:-:*:*:*
cpe:2.3:a:jenkins:jenkins:*:*:*:*:lts:*:*:*

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