CVE-2026-28509 LangBot has a Cross Site Scripting(XSS) Vulnerability
Attackers can inject malicious scripts into the LangBot web UI via raw HTML rendering, potentially compromising user sessions or executing code.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-28509?
CVE-2026-28509 is a medium-severity cross-site scripting vulnerability in langbot-app LangBot, published on 6 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-28509?
It affects 1 product.
Products include Langbot Langbot.
How do I fix CVE-2026-28509?
No fix has been published for CVE-2026-28509 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-28509 being exploited?
There is no known exploitation of CVE-2026-28509 in the wild and no public exploit code.
Sources
Also known as GHSA-w8gq-g4pc-xh3h.