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.
CVE-2025-26621
This high-severity CVE scores 7.6 under NVD CVSS v3. EPSS exploit probability: 0.7%, top 27% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.6
- EG Score
- 7.6(medium)
- EG Risk
- —
- EPSS
- 27.8%
- KEV
- Not listed
Published
May 19, 2025
Last Modified
August 6, 2025
References (2)
- security-advisories@githubhttps://github.com/OpenCTI-Platform/opencti/security/advisories/GHSA-gq63-jm3h-374p
- security-advisories@githubhttps://github.com/OpenCTI-Platform/opencti/security/advisories/GHSA-mf88-g2wq-p7qm
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| pycti | 1.2.1 ... 6.5.1 (291 versions) | 6.5.2 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 46× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 14:07 UTCEPSS rescore
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- 2026-07-07 01:21 UTCOSV refresh
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- 2026-06-18 12:05 UTCOSV refresh
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- 2026-05-30 05:03 UTCEG score recompute
- 2026-05-29 13:44 UTCEPSS rescore
Related CVEs(same CWE)
Same CWE
10 shownCWE-94
Frequently asked(5)
What is CVE-2025-26621?
When was CVE-2025-26621 disclosed?
Is CVE-2025-26621 actively exploited?
What is the CVSS score of CVE-2025-26621?
How do I remediate CVE-2025-26621?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-26621
Is Your Infrastructure Affected by CVE-2025-26621?
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