How severe is CVE-2021-21686?

CVE-2021-21686 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-21686 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21686?

CVE-2021-21686 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-2021-21686?

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-2021-21686 published?

CVE-2021-21686 was published on 2021-11-04 and last updated on 2026-06-17.

CVE-2021-21686

CVE-2021-21686 is a high-severity vulnerability in Jenkins with a CVSS 3.x base score of 8.1. 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: High (CVSS 3.x base score 8.1)
CVSS v2: 5.8
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-59
Affected product: Jenkins
Published: 2021-11-04
Last modified: 2026-06-17

Description

File path filters in the agent-to-controller security subsystem of Jenkins 2.318 and earlier, LTS 2.303.2 and earlier do not canonicalize paths, allowing operations to follow symbolic links to outside allowed directories.

Frequently asked questions

What is CVE-2021-21686?: File path filters in the agent-to-controller security subsystem of Jenkins 2.318 and earlier, LTS 2.303.2 and earlier do not canonicalize paths, allowing operations to follow symbolic links to outside allowed directories.
How severe is CVE-2021-21686?: CVE-2021-21686 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-21686 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21686?: CVE-2021-21686 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-2021-21686?: 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-2021-21686 published?: CVE-2021-21686 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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