Bug ID 2288381: VIOL_REQUEST_MAX_LENGTH is not triggered when the login request size exceeds max_login_request_body_buffer_size

Last Modified: Jul 28, 2026

Affected Product(s):
BIG-IP ASM(all modules)

Fixed In:
21.0.0.3, 17.5.1.8

Opened: Apr 23, 2026

Severity: 4-Minor

Symptoms

VIOL_REQUEST_MAX_LENGTH is not triggered when the size of a login request exceeds the max_login_request_body_buffer_size

Impact

Violation VIOL_REQUEST_MAX_LENGTH not triggered

Conditions

A policy with a login page configured with authentication_type=request-body is set, and max_login_request_body_buffer_size is configured to a smaller value than the size of the incoming request.

Workaround

Modify the logic so that if auth_headers_count == 0 and auth_type includes authentication headers, set auth_type to FORM; otherwise, retain the original auth_type.

Fix Information

Reset auth_type to FORM only for authentication types that rely on authorization headers. Otherwise, retain the original auth_type and detect it as a login request.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips