Bug 2482360 (CVE-2026-45104)

Summary: CVE-2026-45104 mapserver: MapServer: Denial of Service via malformed SLD in WMS SLD_BODY parameter
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in MapServer. A remote attacker can exploit this vulnerability by sending a specially crafted Styled Layer Descriptor (SLD) via the Web Map Service (WMS) SLD_BODY parameter. This can lead to a NULL pointer dereference, causing a Denial of Service (DoS) condition.
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Bug Depends On: 2482506, 2482505    
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Description OSIDB Bzimport 2026-05-27 20:01:34 UTC 
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.