Medium severity · published Mar 6, 2026
CVE-2026-28509
LangBot has a Cross Site Scripting(XSS) Vulnerability
5.4
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 10% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LA
LangBot · langbot-app
< 4.8.7 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-28509
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-28509
Patch
https://github.com/langbot-app/LangBot/commit/614621ab7b84fe50da3c6137705cde5a99429866
Exploit
https://github.com/langbot-app/LangBot/security/advisories/GHSA-w8gq-g4pc-xh3h
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