CVE-2026-28509

Name: CVE-2026-28509
Creator: NVD / NIST
Published: 2026-03-06T05:16:35.59+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 0.19%

Last modified Jun 17, 2026

CVE-2026-28509 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. 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. EPSS estimates a 0.19% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.19%

8.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Langbot	Langbot	< 4.8.7

References

https://github.com/langbot-app/LangBot/commit/614621ab7b84fe50da3c6137705cde5a99429866Patch
https://github.com/langbot-app/LangBot/security/advisories/GHSA-w8gq-g4pc-xh3hExploit, Vendor Advisory

Timeline

Published: Mar 6, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-28509?

How severe is CVE-2026-28509?

CVE-2026-28509 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.19% probability of exploitation in the next 30 days.

How do I fix CVE-2026-28509?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-28509?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST