How severe is CVE-2021-3859?

CVE-2021-3859 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-3859 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-2021-3859?

CVE-2021-3859 primarily affects Redhat Jboss Enterprise Application Platform. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3859?

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-2021-3859 published?

CVE-2021-3859 was published on 2022-08-26 and last updated on 2026-06-17.

CVE-2021-3859

CVE-2021-3859 is a high-severity vulnerability in Redhat Jboss Enterprise Application Platform 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. The underlying weakness is classified as CWE-214.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-214
Affected product: Redhat Jboss Enterprise Application Platform
Published: 2022-08-26
Last modified: 2026-06-17

Description

A flaw was found in Undertow that tripped the client-side invocation timeout with certain calls made over HTTP2. This flaw allows an attacker to carry out denial of service attacks.

Frequently asked questions

What is CVE-2021-3859?: A flaw was found in Undertow that tripped the client-side invocation timeout with certain calls made over HTTP2. This flaw allows an attacker to carry out denial of service attacks.
How severe is CVE-2021-3859?: CVE-2021-3859 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-3859 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-2021-3859?: CVE-2021-3859 primarily affects Redhat Jboss Enterprise Application Platform. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3859?: 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-2021-3859 published?: CVE-2021-3859 was published on 2022-08-26 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.3:*:*:*:*:*:*:*
cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.4:*:*:*:*:*:*:*
cpe:2.3:a:redhat:single_sign-on:7.4.10:*:*:*:*:*:*:*
cpe:2.3:a:redhat:single_sign-on:7.5.1:*:*:*:*:*:*:*
cpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
cpe:2.3:a:netapp:cloud_secure_agent:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:oncommand_insight:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:oncommand_workflow_automation:-:*:*:*:*:*:*:*

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