How severe is CVE-2021-21691?

CVE-2021-21691 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21691 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21691?

CVE-2021-21691 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-2021-21691?

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

When was CVE-2021-21691 published?

CVE-2021-21691 was published on 2021-11-04 and last updated on 2026-06-17.

CVE-2021-21691

CVE-2021-21691 is a critical-severity vulnerability in Jenkins with a CVSS 3.x base score of 9.8. 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-59.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-59
Affected product: Jenkins
Published: 2021-11-04
Last modified: 2026-06-17

Description

Creating symbolic links is possible without the 'symlink' agent-to-controller access control permission in Jenkins 2.318 and earlier, LTS 2.303.2 and earlier.

Frequently asked questions

What is CVE-2021-21691?: Creating symbolic links is possible without the 'symlink' agent-to-controller access control permission in Jenkins 2.318 and earlier, LTS 2.303.2 and earlier.
How severe is CVE-2021-21691?: CVE-2021-21691 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21691 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21691?: CVE-2021-21691 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-2021-21691?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-21691 published?: CVE-2021-21691 was published on 2021-11-04 and last updated on 2026-06-17.

References

https://www.jenkins.io/security/advisory/2021-11-04/#SECURITY-2455

Affected products (2)

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

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