CVE-2026-45104

HIGH

MapServer: NULL pointer dereference in SLD `<ElseFilter>` rule parsing reachable via WMS `SLD_BODY`

Title source: cna
STIX 2.1

Description

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.

References (1)

Core 1
Core References

Scores

CVSS v3 7.5
EPSS 0.0028
EPSS Percentile 19.3%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Details

CWE
CWE-129 CWE-476
Status published
Products (2)
MapServer/MapServer >= 6.4.0, < 8.6.3
osgeo/mapserver 6.4.0 - 8.6.3
Published May 27, 2026
Tracked Since May 28, 2026