CVE-2025-26621 OpenCTI vulnerable to Denial of Service through web hook
Users with customization rights can inject JavaScript via webhooks to cause denial of service or execute code in OpenCTI.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-26621?
CVE-2025-26621 is a high-severity code injection vulnerability in OpenCTI-Platform opencti, published on 19 May 2025. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to version 6.5.2, any user with the capability manage customizations can edit webhook that will execute javascript code. This can be abused to cause a denial of service attack by prototype pollution, making the node js server running the OpenCTI frontend become unavailable. Version 6.5.2 fixes the issue.
Which versions are affected by CVE-2025-26621?
1 open source package ship an affected version, including pycti. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pycti PyPI | All versions | 6.5.2 |
Products include Citeum Opencti.
How do I fix CVE-2025-26621?
Upgrade pycti to 6.5.2 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2025-26621 being exploited?
There is no known exploitation of CVE-2025-26621 in the wild and no public exploit code.
Other vulnerabilities in OpenCTI-Platform opencti
- CVE-2026-27960 OpenCTI privilege escalation and unauthenticated access via default admin account
- CVE-2026-39980 OpenCTI affected by RCE via notifier template
- CVE-2025-24977 OpenCTI has remote code execution and sensitive secrets exposed through web hook
- CVE-2024-26139 OpenCTI Authenticated Privilege Escalation
- CVE-2024-45404 OpenCTI's lack of Rate Limit lead to OTP brute forcing
Sources
Also known as PYSEC-2025-180.