How severe is CVE-2026-28509?

CVE-2026-28509 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2026-28509 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-28509?

CVE-2026-28509 affects Langbot. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-28509?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-28509 have an EU (EUVD) identifier?

Yes. CVE-2026-28509 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9985.

When was CVE-2026-28509 published?

CVE-2026-28509 was published on 2026-03-06 and last updated on 2026-06-17.

CVE-2026-28509

CVE-2026-28509 is a medium-severity vulnerability in Langbot with a CVSS 3.x base score of 6.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.3)
EPSS exploit prediction: 0% (8th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-9985
Weakness: CWE-79
Affected product: Langbot
Published: 2026-03-06
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-28509?: 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.
How severe is CVE-2026-28509?: CVE-2026-28509 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2026-28509 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-28509?: CVE-2026-28509 affects Langbot. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-28509?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-28509 have an EU (EUVD) identifier?: Yes. CVE-2026-28509 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9985.
When was CVE-2026-28509 published?: CVE-2026-28509 was published on 2026-03-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:langbot:langbot:*:*:*:*:*:*:*:*

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