XSS in Deepseek Deepseek-R1

CVE-2025-26210

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.006 (45.7th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-26210: held from 0.006 to 0.006.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-26210?
CVE-2025-26210 is a high-severity vulnerability in Deepseek Deepseek-R1, classified under Cross-site Scripting. CVSS score: 8.8/10. Published 2025-09-03.
How severe is CVE-2025-26210?
High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2025-26210 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.