How severe is CVE-2021-21659?

CVE-2021-21659 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.

Is CVE-2021-21659 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 67% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21659?

CVE-2021-21659 affects Jenkins Urltrigger. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21659?

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-2021-21659 published?

CVE-2021-21659 was published on 2021-05-25 and last updated on 2026-06-17.

CVE-2021-21659

CVE-2021-21659 is a high-severity vulnerability in Jenkins Urltrigger with a CVSS 3.x base score of 8.1. Its EPSS exploit-prediction score of 67% places it in the 99th percentile, indicating an elevated likelihood of exploitation.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 5.5
EPSS exploit prediction: 67% (99th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Jenkins Urltrigger
Published: 2021-05-25
Last modified: 2026-06-17

Description

Jenkins URLTrigger Plugin 0.48 and earlier does not configure its XML parser to prevent XML external entity (XXE) attacks.

Frequently asked questions

What is CVE-2021-21659?: Jenkins URLTrigger Plugin 0.48 and earlier does not configure its XML parser to prevent XML external entity (XXE) attacks.
How severe is CVE-2021-21659?: CVE-2021-21659 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2021-21659 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 67% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21659?: CVE-2021-21659 affects Jenkins Urltrigger. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21659?: 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-2021-21659 published?: CVE-2021-21659 was published on 2021-05-25 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:jenkins:urltrigger:*:*:*:*:*:jenkins:*:*

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