Vulnerability Description
Bokeh is an interactive visualization library written in Python. In versions 3.8.1 and below, if a server is configured with an allowlist (e.g., dashboard.corp), an attacker can register a domain like dashboard.corp.attacker.com (or use a subdomain if applicable) and lure a victim to visit it. The malicious site can then initiate a WebSocket connection to the vulnerable Bokeh server. Since the Origin header (e.g., http://dashboard.corp.attacker.com/) matches the allowlist according to the flawed logic, the connection is accepted. Once connected, the attacker can interact with the Bokeh server on behalf of the victim, potentially accessing sensitive data, or modifying visualizations. This issue is fixed in version 3.8.2.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Bokeh | Bokeh | < 3.8.2 |
Related Weaknesses (CWE)
References
- https://github.com/bokeh/bokeh/commit/cedd113b0e271b439dce768671685cf5f861812ePatch
- https://github.com/bokeh/bokeh/security/advisories/GHSA-793v-589g-574vVendor AdvisoryExploit
- https://aydinnyunus.github.io/2026/01/24/bokeh-websocket-hijacking-cve-2026-2188ExploitMitigationThird Party Advisory
FAQ
What is CVE-2026-21883?
CVE-2026-21883 is a vulnerability with a CVSS score of 5.4 (MEDIUM). Bokeh is an interactive visualization library written in Python. In versions 3.8.1 and below, if a server is configured with an allowlist (e.g., dashboard.corp), an attacker can register a domain like...
How severe is CVE-2026-21883?
CVE-2026-21883 has been rated MEDIUM with a CVSS base score of 5.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-21883?
Check the references section above for vendor advisories and patch information. Affected products include: Bokeh Bokeh.