[CI] OpenIdConnectAuthIT testAuthenticateWithImplicitFlow failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-periodic #3522 / openjdk22_checkpart2_java-matrix
• elasticsearch-pull-request #26682 / part-2
• elasticsearch-pull-request #26675 / part-2

Reproduction Line:

./gradlew ":x-pack:qa:oidc-op-tests:javaRestTest" --tests "org.elasticsearch.xpack.security.authc.oidc.OpenIdConnectAuthIT.testAuthenticateWithImplicitFlow" -Dtests.seed=506CC0D96DAB971 -Dtests.locale=de-LU -Dtests.timezone=GB-Eire -Druntime.java=22

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

org.elasticsearch.client.ResponseException: method [POST], host [https://[::1]:34631], URI [/_security/oidc/authenticate], status line [HTTP/1.1 401 Unauthorized]
{"error":{"root_cause":[{"type":"security_exception","reason":"unable to authenticate user [<OIDC Token>] for action [cluster:admin/xpack/security/oidc/authenticate]","header":{"WWW-Authenticate":["Basic realm=\"security\", charset=\"UTF-8\"","Bearer realm=\"security\"","ApiKey"]}}],"type":"security_exception","reason":"unable to authenticate user [<OIDC Token>] for action [cluster:admin/xpack/security/oidc/authenticate]","header":{"WWW-Authenticate":["Basic realm=\"security\", charset=\"UTF-8\"","Bearer realm=\"security\"","ApiKey"]}},"status":401}

Issue Reasons:

• [main] 3 failures in test testAuthenticateWithImplicitFlow (2.2% fail rate in 136 executions)
• [main] 2 failures in step part-2 (3.8% fail rate in 52 executions)
• [main] 2 failures in pipeline elasticsearch-pull-request (3.8% fail rate in 52 executions)

Note:
This issue was created using new test triage automation. Please report issues or feedback to es-delivery.

[elasticsearchmachine]

This has been muted on branch main

Mute Reasons:

• [main] 3 failures in test testAuthenticateWithImplicitFlow (2.2% fail rate in 136 executions)
• [main] 2 failures in step part-2 (3.8% fail rate in 52 executions)
• [main] 2 failures in pipeline elasticsearch-pull-request (3.8% fail rate in 52 executions)

Build Scans:

• elasticsearch-periodic #3522 / openjdk22_checkpart2_java-matrix
• elasticsearch-pull-request #26682 / part-2
• elasticsearch-pull-request #26675 / part-2

[elasticsearchmachine]

Pinging @elastic/es-delivery (Team:Delivery)

[elasticsearchmachine]

Pinging @elastic/es-security (Team:Security)

[gwbrown]

I suspect #111396, #109871, and #100783 will share a root cause with this, as the failures are quite similar.

I was looking into one of those earlier when I found a build with a failure in this suite and a similar error after Tim's logging changes, which is in the same suite, which lists the fully-expanded cause as:
Authentication to realm c2id-proxy failed - Failed to authenticate user with OpenID Connect (Caused by org.elasticsearch.ElasticsearchSecurityException: Failed to get claims from the Userinfo Endpoint.; Caused by java.util.concurrent.TimeoutException: Connection lease request time out)