CVE-2026-45104 — MapServer: NULL pointer dereference in SLD `<ElseFilter>` rule parsing reachable via WMS `SLD_BODY`

Description (CNA)

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 one class. When the rule has no symbolizer (a structurally valid SLD), msSLDParseRule adds zero, and _SLDApplyRuleValues ends up indexing _class[-1], resulting in a NULL pointer dereference. A 200-byte well-formed SLD via the WMS SLD_BODY= parameter is enough to trigger this, no auth required. This vulnerability is fixed in 8.6.3.

Affected (CNA)

Vendor / product	Versions
MapServer / MapServer	affected >= 6.4.0, < 8.6.3

CWE

CWE-129, CWE-476

References

https://github.com/MapServer/MapServer/security/advisories/GHSA-4h8g-378q-r75m

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.