Skip to main content
VulnerabilityPublished Updated

CVE-2025-26210: DeepSeek R1 · Cross-site Scripting

Source CVE Database V5

0

Not known to be exploited · CVSS 8.8 High.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Sep 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

AI-suggested

  1. Implement strict Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts within the run-html-chat.deepseeksvc.com domain.
  2. Employ input validation and output encoding on all user-supplied data that is rendered in chat interfaces to prevent injection of malicious scripts.
  3. Use web application firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting DeepSeek services.
  4. Educate users on the risks of interacting with unsolicited or suspicious chat messages and links, emphasizing cautious behavior to reduce successful social engineering.
  5. Monitor network traffic and logs for unusual activities indicative of exploitation attempts, such as anomalous script execution or unexpected requests to the chat domain.
  6. Isolate the DeepSeek chat service in a segmented network environment to limit lateral movement if exploitation occurs.
  7. Engage with DeepSeek vendors or service providers to obtain patches or updates as soon as they become available and plan for timely deployment.
  8. Consider temporary disabling or restricting access to the affected chat services if feasible until a fix is applied.

Description

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.

References

Community reviews

Loading reviews…