axios versions from 0.28.0 before 0.33.0 and from 1.0.0 before 1.18.0 contain uncontrolled recursion in formDataToJSON (exposed as axios.formToJSON() and used internally when serializing FormData with Content-Type: application/json). When an application passes attacker-controlled FormData field names, a field name with thousands of nested bracket-delimited segments causes unbounded recursion in buildPath(), exhausting the JavaScript call stack (RangeError: Maximum call stack size exceeded) and causing denial of service for that request, or process termination in applications without appropriate error handling.

axios versions 0.28.0 and later contain uncontrolled recursion in formDataToJSON when processing FormData field names with deeply nested bracket segments. Attackers can supply FormData with field names containing thousands of nested brackets to exhaust the JavaScript call stack and trigger RangeError, causing request failure or process termination in applications that do not handle the exception.