What is CVE-2026-45104?

CVE-2026-45104 is a high-severity vulnerability in Mapserver, classified under Improper Validation of Array Index. CVSS score: 7.5/10. Published 2026-05-27.

How severe is CVE-2026-45104?

High severity. CVSS v3 base score is 7.5 out of 10.

NULL pointer dereference in Mapserver

CVE-2026-45104

MapServer is a system for developing web-based GIS applications. From 6.4.0 to before 8.6.3, msSLDParseUserStyle always calls _SLDApplyRuleValues(psRule, psLayer, 1); for any <Rule> carrying <ElseFilter/> — it assumes msSLDParseRule added…

EPSS: 0.001 (16.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Mapserver — versions >= 6.4.0, < 8.6.3
Osgeo Mapserver

Weakness classification (CWE)

CWE-129 — Improper Validation of Array Index
CWE-476 — NULL Pointer Dereference

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-45104?: CVE-2026-45104 is a high-severity vulnerability in Mapserver, classified under Improper Validation of Array Index. CVSS score: 7.5/10. Published 2026-05-27.
How severe is CVE-2026-45104?: High severity. CVSS v3 base score is 7.5 out of 10.