How severe is CVE-2026-39980?

CVE-2026-39980 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-39980 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-39980?

CVE-2026-39980 affects Citeum Opencti. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-39980?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-39980 have an EU (EUVD) identifier?

Yes. CVE-2026-39980 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20972.

When was CVE-2026-39980 published?

CVE-2026-39980 was published on 2026-04-09 and last updated on 2026-06-17.

CVE-2026-39980

CVE-2026-39980 is a critical-severity vulnerability in Citeum Opencti with a CVSS 3.x base score of 9.1. 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-1336.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 1% (40th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-20972
Weakness: CWE-1336
Affected product: Citeum Opencti
Published: 2026-04-09
Last modified: 2026-06-17

Description

OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 6.9.5, the safeEjs.ts file does not properly sanitize EJS templates. Users with the Manage customization capability can run arbitrary JavaScript in the context of the OpenCTI platform process during notifier template execution. This vulnerability is fixed in 6.9.5.

Frequently asked questions

What is CVE-2026-39980?: OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 6.9.5, the safeEjs.ts file does not properly sanitize EJS templates. Users with the Manage customization capability can run arbitrary JavaScript in the context of the OpenCTI platform process during notifier template execution. This vulnerability is fixed in 6.9.5.
How severe is CVE-2026-39980?: CVE-2026-39980 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-39980 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-39980?: CVE-2026-39980 affects Citeum Opencti. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-39980?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-39980 have an EU (EUVD) identifier?: Yes. CVE-2026-39980 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20972.
When was CVE-2026-39980 published?: CVE-2026-39980 was published on 2026-04-09 and last updated on 2026-06-17.

References

Affected products (1)

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

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