CVE-2026-35210 OpenCTI: Authorization Bypass via `synchronized-upsert` HTTP Header Injection
Authenticated users can bypass security markings and confidence validation by injecting a specific HTTP header, allowing unauthorized data manipulation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-35210?
CVE-2026-35210 is a high-severity authentication bypass vulnerability in OpenCTI-Platform opencti, published on 8 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 7.260326.0, an authorization bypass vulnerability in OpenCTI allows any authenticated user with KNOWLEDGE_KNUPDATE permission to bypass Confidence Level validation and Object Marking restrictions by injecting the synchronized-upsert: true HTTP header, enabling attackers to downgrade confidence levels, remove security markings such as TLP:RED, manipulate relationships, and affect STIX object types including Indicators, ThreatActors, Malware, and Reports. This issue is fixed in version 7.260326.0.
Which versions are affected by CVE-2026-35210?
1 open source package ship an affected version, including pycti. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pycti PyPI | All versions | 7.260326.0 |
Products include Citeum Opencti.
How do I fix CVE-2026-35210?
Upgrade pycti to 7.260326.0 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-35210 being exploited?
There is no known exploitation of CVE-2026-35210 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 GHSA-36fr-4m54-94mj, PYSEC-2026-3445.