Fix route processing for AppSec

[y9v]

What does this PR do?

Motivation:
When Warden invokes Devise::FailureApp directly, the router is bypassed so ActionDispatch::Routing::RouteSet never runs and path_parameters is nil in env. This causes a NoMethodError.

Change log entry
Yes. AppSec: Fix an exception for unauthorized requests when using Devise with Rails.

Additional Notes:
SCRS-2273

How to test the change?
CI.

[datadog-prod-us1-6]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 90.02% (-0.01%)

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🔗 Commit SHA: c12beb0 | Docs | Datadog PR Page | Give us feedback!}

[Strech]

Thanks for the fix, I left few minor suggestions

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-07-03 09:20:50

Comparing candidate commit c12beb0 in PR branch appsec-fix-route-processing-for-rails with baseline commit 3ec5c3c in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 48 metrics, 1 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'