CVE-2026-28509

Severity CVSS v4.0:

Pending analysis

Type:

CWE-79 Cross-Site Scripting (XSS)

Publication date:

06/03/2026

Last modified:

09/03/2026

Description

LangBot is a global IM bot platform designed for LLMs. Prior to version 4.8.7, LangBot’s web UI renders user-supplied raw HTML using rehypeRaw, which can lead to a cross-site scripting (XSS) vulnerability. This issue has been patched in version 4.8.7.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 6.30 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): Required
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): Low
Availability (A): None

Base Score 3.x

6.30

Severity 3.x

MEDIUM

References to Advisories, Solutions, and Tools

https://github.com/langbot-app/LangBot/commit/614621ab7b84fe50da3c6137705cde5a99429866
https://github.com/langbot-app/LangBot/security/advisories/GHSA-w8gq-g4pc-xh3h