How severe is CVE-2021-21609?

CVE-2021-21609 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2021-21609 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21609?

CVE-2021-21609 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-2021-21609?

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

When was CVE-2021-21609 published?

CVE-2021-21609 was published on 2021-01-13 and last updated on 2026-06-17.

CVE-2021-21609

CVE-2021-21609 is a medium-severity vulnerability in Jenkins with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-863
Affected product: Jenkins
Published: 2021-01-13
Last modified: 2026-06-17

Description

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not correctly match requested URLs to the list of always accessible paths, allowing attackers without Overall/Read permission to access some URLs as if they did have Overall/Read permission.

Frequently asked questions

What is CVE-2021-21609?: Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not correctly match requested URLs to the list of always accessible paths, allowing attackers without Overall/Read permission to access some URLs as if they did have Overall/Read permission.
How severe is CVE-2021-21609?: CVE-2021-21609 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2021-21609 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21609?: CVE-2021-21609 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-2021-21609?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-21609 published?: CVE-2021-21609 was published on 2021-01-13 and last updated on 2026-06-17.

References

https://www.jenkins.io/security/advisory/2021-01-13/#SECURITY-2047

Affected products (2)

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

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