CVE-2026-33521: BUG-000186514 - ArcGIS Server has a security vulnerability.
There is s denial of service vulnerability in Esri ArcGIS Server versions 12.0 and prior that may allow a remote, unauthenticated attacker to supply crafted requests that may, under exceptional circumstances, consume all available worker threads and deny service to users. A patch is provided for ArcGIS Server software in General Availability and Extended support status, which includes versions 12.0, 11.5, 11.3, and 11.1. Other versions are in mature or retired status, which are not patch eligible. Users working with unlisted versions are advised to upgrade and apply the patch.
Affected Software
Event History
Frequently Asked Questions
Which ArcGIS Server versions can receive a patch?
Patches are provided for ArcGIS Server 12.0, 11.5, 11.3, and 11.1, which are in General Availability or Extended support. Other versions are mature or retired and are not patch eligible.
Does exploitation require authentication or user interaction?
No. A remote, unauthenticated attacker may send crafted requests, and no user interaction is required.
What should organizations running an unlisted version do?
Organizations using an unlisted ArcGIS Server version should upgrade to a supported version and apply the patch. The available information does not identify a workaround for versions that are not patch eligible.