How severe is CVE-2021-3636?

CVE-2021-3636 has a CVSS 3.x base score of 4.6, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-3636 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3636?

CVE-2021-3636 affects Redhat Openshift. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3636?

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

When was CVE-2021-3636 published?

CVE-2021-3636 was published on 2021-07-30 and last updated on 2026-06-17.

CVE-2021-3636

CVE-2021-3636 is a medium-severity vulnerability in Redhat Openshift with a CVSS 3.x base score of 4.6. 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-287.

Key facts

Severity: Medium (CVSS 3.x base score 4.6)
CVSS v2: 4.1
EPSS exploit prediction: 0% (19th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Redhat Openshift
Published: 2021-07-30
Last modified: 2026-06-17

Description

It was found in OpenShift, before version 4.8, that the generated certificate for the in-cluster Service CA, incorrectly included additional certificates. The Service CA is automatically mounted into all pods, allowing them to safely connect to trusted in-cluster services that present certificates signed by the trusted Service CA. The incorrect inclusion of additional CAs in this certificate would allow an attacker that compromises any of the additional CAs to masquerade as a trusted in-cluster service.

Frequently asked questions

What is CVE-2021-3636?: It was found in OpenShift, before version 4.8, that the generated certificate for the in-cluster Service CA, incorrectly included additional certificates. The Service CA is automatically mounted into all pods, allowing them to safely connect to trusted in-cluster services that present certificates signed by the trusted Service CA. The incorrect inclusion of additional CAs in this certificate would allow an attacker that compromises any of the additional CAs to masquerade as a trusted in-cluster service.
How severe is CVE-2021-3636?: CVE-2021-3636 has a CVSS 3.x base score of 4.6, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-3636 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3636?: CVE-2021-3636 affects Redhat Openshift. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3636?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3636 published?: CVE-2021-3636 was published on 2021-07-30 and last updated on 2026-06-17.

References

https://bugzilla.redhat.com/show_bug.cgi?id=1978621

Affected products (1)

cpe:2.3:a:redhat:openshift:*:*:*:*:*:*:*:*

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