What is CVE-2026-39980?

CVE-2026-39980 is a critical-severity vulnerability in Opencti-platform Opencti, classified under Improper Neutralization of Special Elements Used in a Template Engine. CVSS score: 9.1/10. Published 2026-04-09.

How severe is CVE-2026-39980?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Opencti-platform Opencti

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 arbit…

EPSS: 0.000 (14.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.

Affected products

Opencti-platform Opencti — versions < 6.9.5

Weakness classification (CWE)

CWE-1336 — Improper Neutralization of Special Elements Used in a Template Engine

References

https://github.com/OpenCTI-Platform/opencti/security/advisories/GHSA-jv9r-jw2f-rhrf (x_refsource_CONFIRM)
https://github.com/OpenCTI-Platform/opencti/releases/tag/6.9.5 (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-39980?: CVE-2026-39980 is a critical-severity vulnerability in Opencti-platform Opencti, classified under Improper Neutralization of Special Elements Used in a Template Engine. CVSS score: 9.1/10. Published 2026-04-09.
How severe is CVE-2026-39980?: Critical severity. CVSS v3 base score is 9.1 out of 10.