How severe is CVE-2026-21886?

CVE-2026-21886 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-21886 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21886?

CVE-2026-21886 affects Citeum Opencti. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21886?

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

Does CVE-2026-21886 have an EU (EUVD) identifier?

Yes. CVE-2026-21886 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12578.

When was CVE-2026-21886 published?

CVE-2026-21886 was published on 2026-03-17 and last updated on 2026-06-17.

CVE-2026-21886

CVE-2026-21886 is a medium-severity vulnerability in Citeum Opencti with a CVSS 3.x base score of 6.5. 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-285.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12578
Weakness: CWE-285
Affected product: Citeum Opencti
Published: 2026-03-17
Last modified: 2026-06-17

Description

OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to version 6.9.1, the GraphQL mutations "IndividualDeletionDeleteMutation" is intended to allow users to delete individual entity objects respectively. However, it was observed that this mutation can be misused to delete unrelated and sensitive objects such as analyses reports etc. This behavior stems from the lack of validation in the API to ensure that the targeted object is contextually related to the mutation being executed. Version 6.9.1 fixes the issue.

Frequently asked questions

What is CVE-2026-21886?: OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to version 6.9.1, the GraphQL mutations "IndividualDeletionDeleteMutation" is intended to allow users to delete individual entity objects respectively. However, it was observed that this mutation can be misused to delete unrelated and sensitive objects such as analyses reports etc. This behavior stems from the lack of validation in the API to ensure that the targeted object is contextually related to the mutation being executed. Version 6.9.1 fixes the issue.
How severe is CVE-2026-21886?: CVE-2026-21886 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-21886 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21886?: CVE-2026-21886 affects Citeum Opencti. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21886?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21886 have an EU (EUVD) identifier?: Yes. CVE-2026-21886 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12578.
When was CVE-2026-21886 published?: CVE-2026-21886 was published on 2026-03-17 and last updated on 2026-06-17.

References

https://github.com/OpenCTI-Platform/opencti/security/advisories/GHSA-mhmx-j75v-2m6x

Affected products (1)

cpe:2.3:a:citeum:opencti:*:*:*:*:*:*:*:*

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