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Fencer Intel
medium 6.1

CVE-2025-50733 json

NextChat contains a cross-site scripting (XSS) vulnerability in the HTMLPreview component of artifacts.tsx that allows attackers to execute…

published last yr. modified 4mo ago also EUVD-2025-25594

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

NextChat contains a cross-site scripting (XSS) vulnerability in the HTMLPreview component of artifacts.tsx that allows attackers to execute arbitrary JavaScript code when HTML content is rendered in the AI chat interface. The vulnerability occurs because user-influenced HTML from AI responses is rendered in an iframe with 'allow-scripts' sandbox permission without proper sanitization. This can be exploited through specifically crafted prompts that cause the AI to generate malicious HTML/JavaScript code. When a user views the HTML preview, the injected JavaScript executes in the user's browser context, potentially allowing attackers to exfiltrate sensitive information (including API keys stored in localStorage), perform actions on behalf of the user, and steal session data.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/fai1424/Vulnerability-Research/blob/main/CVE-2025-50733/README.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Classification

Weakness
  • 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.