CVE-2025-26621
OpenCTI vulnerable to Denial of Service through web hook
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
OpenCTI vulnerable to Denial of Service through web hook
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.
- Record
CVE-2025-26621- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
EUVDEUVD-2025-15725
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.
- Record
EUVD-2025-15725- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:H - Updated
- 2026-11-02
NVD
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.
- Record
CVE-2025-26621- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:H - CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H - Weakness
- CWE-94, CWE-1321
- Updated
- 2026-11-02
OSV
OpenCTI vulnerable to Denial of Service through web hook
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.
- Record
CVE-2025-26621- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:H - Weakness
- CWE-94
- Updated
- 2026-11-02
OSVPYSEC-2025-180
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.
- Record
PYSEC-2025-180- CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
pyctiPyPI |
before 6.5.2, plus listed versions 1.2.11.2.111.2.121.2.131.2.14 Show 45 moreShow less1.2.151.2.21.2.41.2.92.0.02.0.12.0.22.0.32.1.102.1.112.1.122.1.132.1.32.1.42.1.52.1.62.1.72.1.82.1.93.0.03.0.13.0.23.0.33.1.03.1.13.1.23.2.03.2.13.2.23.2.33.2.43.2.53.2.63.2.73.3.03.3.13.3.23.3.34.0.04.0.14.0.24.0.34.0.44.0.54.0.6 |
6.5.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-26621 is a high vulnerability (CVSS 7.6) in Citeum Opencti, published May 19, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.42%, the 36th percentile. Fixed in pycti 6.5.2.
References
Left out here: 241 versions. The JSON record has them.