Issue Summary

When a Jira Service Management portal link contains a newline character (encoded as %0A) within a query parameter (for example, in the description or summary fields), the redirect flow to id.atlassian.com fails for managed users.

The JSM two-step login service passes the continue parameter to Identity with only single-encoding. During the authentication handshake, Identity decodes the %0A into a literal newline. Because literal newlines are illegal in URLs, Identity's security validation rejects the continue URL and redirects the user to the Atlassian Start page (start.atlassian.com), causing the loss of all pre-filled form data.

Steps to Reproduce

1. Construct a JSM portal link that includes a newline character in a query parameter, such as: https://<site>.atlassian.net/servicedesk/customer/portal/1/create/1?description=Line1%0ALine2

1. Open this link in an Incognito/Private browser window to ensure a fresh session is required.

1. Enter a managed email address (one subject to SSO) in the JSM login prompt.

1. Complete the SSO authentication process.

Expected Results

After authentication, the user should be redirected back to the specific JSM portal form with the description field pre-populated with "Line1" and "Line2".

Actual Results

The user is redirected to the Atlassian Start page (https://start.atlassian.com) or the Portal Home page. The specific form is never reached, and all pre-filled data is lost.

Workaround

Currently, there is no known workaround to preserve the pre-filled data during the SSO redirect. Users must manually navigate to the form and enter the data, or ensure they have an active Atlassian session before clicking the pre-filled link.