DeepSeek R1 through V3.1 allows XSS, as demonstrated by JavaScript execution in the context of the run-html-chat.deepseeksvc.com domain.
Date: 2025-09
Affected: deepseek/deepseek-r1, deepseek/deepseek-v2, deepseek/deepseek-v3
Attack vector: xss
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2025-26210
CWE: CWE-79
CVSS: 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)

DeepSeek R1 through V3.1 allows XSS, as demonstrated by JavaScript execution in the context of the run-html-chat.deepseeksvc.com domain. NOTE: some third parties have indicated that this is intended behavior.


Mitigations:

Architectural layers (MAESTRO):