Is CVE-2026-28509 in the CISA KEV catalog?

No. CVE-2026-28509 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-28509?

CVE-2026-28509 has a CVSS v3 base score of 6.3 (MEDIUM).

What is the EPSS score for CVE-2026-28509?

CVE-2026-28509 has an EPSS score of 0.19% (8th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-28509?

Upgrade langbot to 4.8.7 or later.

CVE & CISA-KEV Catalog

CVE-2026-28509

MEDIUM

6.3

CVSS v3

NVD

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

langbotNVD

Affected:< 4.8.7Fixed in:4.8.7CVE-2026-28509derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.19%probability of exploitation in 30 days

8thpercentile

Low risk: more likely to be exploited than 8% of all known CVEs.

References

Patch1

github.com

Exploit1

github.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-16.