CVE-2025-26621Network attack vector

Service interruption via prototype-polluting webhook JavaScript

Published May 19, 2025 · Updated May 19, 2025

Code injection in OpenCTI before 6.5.2 allows remote authenticated users to interrupt the frontend service through a crafted webhook. Webhook editing executes supplied JavaScript, which can modify object prototype attributes and make the Node.js frontend unavailable. The account must hold the Manage customizations capability; successful exploitation interrupts the frontend service.

CVSS severity7.6
High
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in OpenCTI before 6.5.2 allows remote authenticated users to interrupt the frontend service through a crafted webhook. Webhook editing executes supplied JavaScript, which can modify object prototype attributes and make the Node.js frontend unavailable. The account must hold the Manage customizations capability; successful exploitation interrupts the frontend service.

The record

CVE
CVE-2025-26621
Published
May 19, 2025
Updated
May 19, 2025
Vendor
Filigran
Product
OpenCTI
Classifications
CWE-94, CWE-1321, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 19, 2025CVE publishedPublication date reported by the CVE source.
  2. May 19, 2025Record 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=< 6.5.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Filigran · OpenCTIversion=< 6.5.2

Published CVSS scores

7.6GitHubCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:L/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-94Improper Control of Generation of Code ('Code Injection')
CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
T1499.004Application or System Exploitation

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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