CVE-2026-39980Network attack vector

Authenticated code execution via EJS denylist bypass

Published Apr 9, 2026 · Updated Apr 9, 2026

Template injection in Filigran OpenCTI before 6.9.5 allows remote authenticated users to execute JavaScript in the platform process. safeEjs.ts checks forbidden property names only when a supplied key is already a string, so coercible non-string keys bypass the sandbox denylist. Manage customization access reaches notifier templates, while CSVMAPPERS access reaches the same evaluator through JsonMapper, granting code execution with the Node.js process's privileges.

CVSS severity9.1
Critical
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Template injection in Filigran OpenCTI before 6.9.5 allows remote authenticated users to execute JavaScript in the platform process. safeEjs.ts checks forbidden property names only when a supplied key is already a string, so coercible non-string keys bypass the sandbox denylist. Manage customization access reaches notifier templates, while CSVMAPPERS access reaches the same evaluator through JsonMapper, granting code execution with the Node.js process's privileges.

The record

CVE
CVE-2026-39980
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Filigran
Product
OpenCTI
Classifications
CWE-1336, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 6.9.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Filigran · OpenCTIversion=< 6.9.5

Published CVSS scores

9.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
7.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1336Improper Neutralization of Special Elements Used in a Template Engine
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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