Is CVE-2026-42030 in the CISA KEV catalog?

No. CVE-2026-42030 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-42030?

CVE-2026-42030 has a CVSS v3 base score of 6.1 (MEDIUM).

What is the EPSS score for CVE-2026-42030?

CVE-2026-42030 has an EPSS score of 0.25% (16th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42030?

Upgrade mapserver on debian unstable to 8.6.2-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-42030

MEDIUM

6.1

CVSS v3

NVD

Description

MapServer is a system for developing web-based GIS applications. From version 6.0 to before version 8.6.2, a reflected XSS vulnerability in MapServer's WMS server allows an unauthenticated attacker to inject arbitrary HTML/JavaScript into the browser of any user who opens a crafted WMS URL. The vulnerability is triggered via FORMAT=application/openlayers combined with an unsanitized SRS parameter in WMS 1.3.0 requests. This issue has been patched in version 8.6.2.

CWE-80

How to fix

Remediation Available

mapserverDebian

Fixed in:8.6.2-1CVE-2026-42030

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 RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.25%probability of exploitation in 30 days

16thpercentile

Low risk: more likely to be exploited than 16% of all known CVEs.

References

Exploit1

github.com

Release Notes1

github.com

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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 2026-05-14.