CVE-2021-3644: wildfly-core allows user with access to management interface to access vault expression, retrieve item from vault

The vulnerability stems from improper sensitivity classification of vault expressions in multi-expression attributes. The commit diff shows the patched version replaced the original two-step check (ExpressionResolver.EXPRESSION_PATTERN followed by VaultReader.STANDARD_VAULT_PATTERN) with a single comprehensive regex (VAULT_EXPRESSION_PATTERN) that scans the entire attribute value. The test case added in VaultExpressionSensitivityTestCase.java demonstrates how an attacker could previously inject a vault expression alongside other content. The isSensitiveValue function's pre-patch logic failed to detect vault expressions when they weren't the sole expression in the attribute, making it the clear vulnerable function.