CVE-2026-27960Network attack vector

Unauthenticated API impersonation of arbitrary users

Published May 5, 2026 · Updated May 5, 2026

Authentication bypass in Filigran OpenCTI 6.6.0 through 6.9.12 allows remote attackers to query the API as any existing user. Filigran has not published the faulty authentication code path or the request data that causes the API to adopt another user's identity. The attack requires no account or user interaction and can assume the default administrator, granting its API privileges and access to threat-intelligence data.

CVSS severity9.8
Critical
EPSS probability1.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Filigran OpenCTI 6.6.0 through 6.9.12 allows remote attackers to query the API as any existing user. Filigran has not published the faulty authentication code path or the request data that causes the API to adopt another user's identity. The attack requires no account or user interaction and can assume the default administrator, granting its API privileges and access to threat-intelligence data.

The record

CVE
CVE-2026-27960
Published
May 5, 2026
Updated
May 5, 2026
Vendor
Filigran
Product
OpenCTI
Classifications
T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 5, 2026CVE publishedPublication date reported by the CVE source.
  2. May 5, 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=>= 6.6.0, < 6.9.13

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Filigran · OpenCTIversion=>= 6.6.0, < 6.9.13

Published CVSS scores

9.8GitHubCVSS:3.1/AV:N/AC:L/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1190Exploit Public-Facing Application

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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