NULL pointer dereference in MapServer - CVE-2026-45104
Published: May 11, 2026
Vulnerability identifier: #VU131001
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-45104
CWE-ID: CWE-476
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: MapServer
Affected software:
MapServer
MapServer
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a null pointer dereference in msSLDParseUserStyle and _SLDApplyRuleValues in MapServer SLD support when processing a crafted SLD ElseFilter rule through the WMS SLD_BODY parameter. A remote attacker can send a specially crafted SLD payload to cause a denial of service.
The issue is reachable through the WMS handler without authentication, and long-lived deployments such as FastCGI, mod_mapserver, or MapScript bindings may terminate the serving process for unrelated in-flight requests.
How to mitigate CVE-2026-45104
Install security update from vendor's website.