This may help?
What can be done if it is taking too long to clear security screening?
If the application has crossed 2-3 months post Review of Eligibility, then the likelihood of it being in security screening is very high. Most security checks are done within 1 month though it can take longer, up to 1 to 2 years, if its in enhanced screening. If it has been more than 2 months since Eligibility Review was “Passed” and security has not yet concluded, then the application may be in enhanced screening.
One can request records from CBSA and CSIS relating to security screening. However, the only way to know for sure if an application is under security screening is through the CBSA notes, as most CBSA notes do not redact security related activities. The CBSA notes will show the status on page# 2 just like the GCMS notes. Additionally, it will also show notes as to when security screening started and if screening has concluded it will also show the date when it was completed.
In cases where the applicant has been waiting for over a year and application seems stuck in security screening you can consider filing a
writ of mandamus. A writ of mandamus is a legal remedy in which a federal court forces a subordinate agency (such as IRCC) to act when the processing delay has been “unreasonable.” To be regarded as unreasonable, a delay must meet the following conditions: the delay in question was longer than the nature of the process required, the applicant and his or her legal counsel were not responsible for the delay and the authority responsible for the delay did not provide satisfactory justification.
When contemplating whether to commence a mandamus application, reference should be made to the processing times listed on the IRCC website. Unreasonable delay can only be determined in comparison to average processing times. In submissions, focus should be on normal processing times and how much the processing time in question has exceeded the average, what the applicant has done to ensure that his/her application is complete and well documented, and reasons why the applicant feels that the officer’s explanation for the delay is unsatisfactory.
In this respect, the Courts in most cases have refused to accept departmental backlogs, or staff shortages as reasonable explanations, nor do they tend to look to the system as a whole. Rather, each case is assessed on its own facts. The question often arises as to whether a background or security check constitutes a justifiable explanation for the delay. The Canadian Bar Association (CBA) explains this in further detail
here. Also see a related federal court case
here.
https://gcmsnotes.com/all-about-security-screening/#ss-timeline