This vulnerability (CVE-2026-72636) in Elasticsearch's wildcard matching helper is due to uncontrolled recursion (CWE-674). The recursive implementation used to resolve wildcard patterns against names lacks bounds on recursion depth and total match operations. When a search request includes a wildcard pattern with many wildcard groups evaluated against a sufficiently long name, it exhausts the thread stack, causing a stack overflow. Elasticsearch treats such stack overflows as unrecoverable, resulting in the affected node shutting down and causing a denial of service. The affected versions explicitly identified are 8.0.0 and 9.0.0. No patch or remediation level has been published by the vendor as of the data provided.

The impact is a denial of service (DoS) condition where an attacker can cause an Elasticsearch node to shut down by sending specially crafted search requests with complex wildcard patterns. This disrupts availability but does not affect confidentiality or integrity. There is no indication of exploitation in the wild at this time.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should consider limiting or filtering wildcard search patterns that could trigger excessive recursion or stack exhaustion. Monitor vendor channels for updates.