NotChatbot WebChat has a stored cross-site scripting (XSS) vulnerability

published 2026-03-18 7 mo ago modified 2026-06-17 4 mo ago also GHSA-w3vx-52j6-9fjp , EUVD-2026-12866

cvss: 5.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits: 0; none known

A stored cross-site scripting (XSS) vulnerability exists in the NotChatbot WebChat widget thru 1.4.4. User-supplied input is not properly sanitized before being stored and rendered in the chat conversation history. This allows an attacker to inject arbitrary JavaScript code which is executed when the chat history is reloaded. The issue is reproducible across multiple independent implementations of the widget, indicating that the vulnerability resides in the product itself rather than in a specific website configuration.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 7 mo ago (2026-03-19)

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CNA	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	@developer.notchatbot/webchat	<=1.5.0	no fix listed

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns 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.

Summary