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Fencer Intel
critical 9.7

CVE-2025-66222 json

DeepChat Cross-Site Scripting(XSS) escalate to Remote Code Execution(RCE)

published 11mo ago modified 22d ago also EUVD-2025-201091

cvss
9.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 51%
public exploits
0
none known

Summary

DeepChat is a smart assistant uses artificial intelligence. In 0.5.0 and earlier, there is a Stored Cross-Site Scripting (XSS) vulnerability in the Mermaid diagram renderer allows an attacker to execute arbitrary JavaScript within the application context. By leveraging the exposed Electron IPC bridge, this XSS can be escalated to Remote Code Execution (RCE) by registering and starting a malicious MCP (Model Context Protocol) server.

Patch / fix

Is CVE-2025-66222 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
11mo ago

Exploit prediction

0.65% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/ThinkInAIXYZ/deepchat/security/advisories/GHSA-v8v5-c872-mf8r referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.7 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
NVD 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected products

  • ThinkInAIXYZ deepchat

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.