Out-of-bounds Write Affecting mapserver package, versions [4.2,8.6.1)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-MAPSERVER-15871017
- published1 Apr 2026
- disclosed27 Mar 2026
- creditkevin-valerio
Introduced: 27 Mar 2026
CVE-2026-33721 (opens in a new tab)How to fix?
Upgrade mapserver to version 8.6.1 or higher.
Overview
Affected versions of this package are vulnerable to Out-of-bounds Write via the SLD parser when processing a crafted SLD containing more than 100 Threshold elements within a ColorMap/Categorize structure. An attacker can cause the process to crash by sending specially crafted requests.