CVE-2026-45104Public exploitNetwork attack vector

Unauthenticated service crash via negative class index

Published May 27, 2026 · Updated May 27, 2026

NULL pointer dereference in MapServer 6.4.0 through 8.6.2 allows remote attackers to crash a WMS worker via an SLD_BODY request. The msSLDParseUserStyle function assumes every ElseFilter rule creates a class and passes one new class to _SLDApplyRuleValues, which reads _class[-1] when a valid rule has no symbolizer. The default-enabled SLD handler requires no authentication; one request terminates a CGI worker or a long-lived FastCGI, mod_mapserver, or MapScript process.

CVSS severity7.5
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in MapServer 6.4.0 through 8.6.2 allows remote attackers to crash a WMS worker via an SLD_BODY request. The msSLDParseUserStyle function assumes every ElseFilter rule creates a class and passes one new class to _SLDApplyRuleValues, which reads _class[-1] when a valid rule has no symbolizer. The default-enabled SLD handler requires no authentication; one request terminates a CGI worker or a long-lived FastCGI, mod_mapserver, or MapScript process.

The record

CVE
CVE-2026-45104
Published
May 27, 2026
Updated
May 27, 2026
Vendor
MapServer
Product
MapServer
Classifications
CWE-129, CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 6.4.0, < 8.6.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MapServer · MapServerversion=>= 6.4.0, < 8.6.3

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-129Improper Validation of Array Index
CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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