For improved safety, passwords and other sensitive fields for authentication should not be included in the request URI during a POST. Instead, they should be in the POST body where they are less likely to be included in log files. With the merge of Gerrit change 305545,[1] the API will now produce a warning if such fields are detected in the URI. This should be deployed to WMF wikis with 1.28.0-wmf.16, see https://www.mediawiki.org/wiki/MediaWiki_1.28/Roadmap for the schedule.

This affects the following modules and fields:

* action=login: 'lgpassword'

* action=clientlogin, action=createaccount, action=linkaccount, and action=changeauthenticationdata: Any fields reported as "sensitive" by action=query&meta=authmanagerinfo or by UI or REDIRECT responses. Currently, this affects the 'password' and 'retype' fields.

The 'lgtoken' field for action=login will now also issue a warning if placed in the request URI. The error code for other tokens being in the request URI has changed from 'mustposttoken' to 'mustpostparams'.

To check if your client's user agent is detected making such submissions, you can also use ApiFeatureUsage[2] and look for '<action>-params-in-query-string' once 1.28.0-wmf.16 is rolled out to wikis your client is logging in to.

It is planned that these warnings will be changed to errors during 1.29. Let's avoid having a repeat of T142155,[3] update your code ASAP instead of waiting until it breaks. Thanks.

[1]: https://gerrit.wikimedia.org/r/#/c/305545/
[2]: https://meta.wikimedia.org/wiki/Special:ApiFeatureUsage
[3]: https://phabricator.wikimedia.org/T142155

Brad Jorsch (Anomie)
Senior Software Engineer
Wikimedia Foundation