username case sensitivity issue

[violoncelloCH]

Affected apps

user_external

Steps to reproduce

1. log in multiple times to the same user via user_external (WebDAV) with different capitalization of the username
2. see different folders in the file system for the different capitalizations but only one user in admin/users
3. from admin/users try to edit parameters (display name / email) and see it getting overwritten back after refresh of the page

Expected behaviour

nextcloud should handle different capitalization of usernames and don't differentiate between them, as it does for users with the user backend "database"

Actual behaviour

strange issues occure as described in "Steps to reproduce"

Server configuration detail

Operating system: Linux 4.4.0-134-generic #160-Ubuntu SMP Wed Aug 15 14:58:00 UTC 2018 x86_64

Webserver: Apache (fpm-fcgi)

Database: mysql 10.0.36

PHP version:

7.2.9-1+ubuntu16.04.1+deb.sury.org+1
Modules loaded: Core, date, libxml, openssl, pcre, zlib, filter, hash, Reflection, SPL, sodium, session, standard, cgi-fcgi, mysqlnd, PDO, xml, apcu, apc, bz2, calendar, ctype, curl, dom, mbstring, fileinfo, ftp, gd, gettext, iconv, igbinary, imagick, intl, json, ldap, exif, mysqli, pdo_mysql, Phar, posix, readline, redis, shmop, SimpleXML, smbclient, sockets, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xmlreader, xmlwriter, xsl, zip, libsmbclient, Zend OPcache

Nextcloud version: 14.0.0 - 14.0.0.19

Updated from an older Nextcloud/ownCloud or fresh install: updated

Where did you install Nextcloud from: official nextclou download

Signing status

Array
(
)

List of activated apps

Enabled:
 - accessibility: 1.0.1
 - activity: 2.7.0
 - bruteforcesettings: 1.1.0
 - cloud_federation_api: 0.0.1
 - comments: 1.4.0
 - dav: 1.6.0
 - federatedfilesharing: 1.4.0
 - federation: 1.4.0
 - files: 1.9.0
 - files_external: 1.5.0
 - files_linkeditor: 1.0.7
 - files_pdfviewer: 1.3.2
 - files_rightclick: 0.8.4
 - files_sharing: 1.6.2
 - files_texteditor: 2.6.0
 - files_trashbin: 1.4.1
 - files_versions: 1.7.1
 - files_videoplayer: 1.3.0
 - firstrunwizard: 2.3.0
 - gallery: 18.1.0
 - groupfolders: 1.3.3
 - impersonate: 1.1.0
 - issuetemplate: 0.4.0
 - logreader: 2.0.0
 - lookup_server_connector: 1.2.0
 - metadata: 0.7.0
 - nextcloud_announcements: 1.3.0
 - notifications: 2.2.1
 - oauth2: 1.2.1
 - onlyoffice: 2.0.4
 - password_policy: 1.4.0
 - previewgenerator: 1.1.0
 - provisioning_api: 1.4.0
 - quota_warning: 1.3.0
 - ransomware_protection: 1.2.0
 - serverinfo: 1.4.0
 - sharebymail: 1.4.0
 - support: 1.0.0
 - survey_client: 1.2.0
 - systemtags: 1.4.0
 - theming: 1.5.0
 - twofactor_backupcodes: 1.3.1
 - updatenotification: 1.4.1
 - user_external: 0.4
 - workflowengine: 1.4.0
Disabled:
 - admin_audit
 - announcementcenter
 - encryption
 - files_accesscontrol
 - files_automatedtagging
 - user_ldap

Configuration (config/config.php)

{
    "instanceid": "***REMOVED SENSITIVE VALUE***",
    "passwordsalt": "***REMOVED SENSITIVE VALUE***",
    "secret": "***REMOVED SENSITIVE VALUE***",
    "trusted_domains": [
        "***REMOVED SENSITIVE VALUE***"
    ],
    "auth.bruteforce.protection.enabled": true,
    "0": [
        ".htaccess",
        "Thumbs.db",
        "thumbs.db"
    ],
    "cron_log": true,
    "activity_expire_days": 33,
    "datadirectory": "***REMOVED SENSITIVE VALUE***",
    "overwrite.cli.url": "***REMOVED SENSITIVE VALUE***",
    "dbtype": "mysql",
    "version": "14.0.0.19",
    "dbname": "***REMOVED SENSITIVE VALUE***",
    "dbhost": "***REMOVED SENSITIVE VALUE***",
    "dbport": "",
    "dbtableprefix": "oc_",
    "mysql.utf8mb4": true,
    "dbuser": "***REMOVED SENSITIVE VALUE***",
    "dbpassword": "***REMOVED SENSITIVE VALUE***",
    "installed": true,
    "enable_previews": true,
    "enabledPreviewProviders": [
        "OC\\Preview\\PNG",
        "OC\\Preview\\JPEG",
        "OC\\Preview\\GIF",
        "OC\\Preview\\BMP",
        "OC\\Preview\\XBitmap",
        "OC\\Preview\\Movie",
        "OC\\Preview\\PDF",
        "OC\\Preview\\MP3",
        "OC\\Preview\\TXT",
        "OC\\Preview\\MarkDown"
    ],
    "preview_max_x": 1024,
    "preview_max_y": 768,
    "preview_max_scale_factor": 1,
    "filesystem_check_changes": 0,
    "filelocking.enabled": "true",
    "htaccess.RewriteBase": "\/",
    "integrity.check.disabled": false,
    "knowledgebaseenabled": false,
    "logfile": "\/srv\/nextclouddata\/nextcloud.log",
    "loglevel": 0,
    "logtimezone": "Europe\/Berlin",
    "log_rotate_size": 104857600,
    "maintenance": false,
    "memcache.local": "\\OC\\Memcache\\APCu",
    "memcache.locking": "\\OC\\Memcache\\Redis",
    "overwriteprotocol": "https",
    "redis": {
        "host": "***REMOVED SENSITIVE VALUE***",
        "password": "***REMOVED SENSITIVE VALUE***",
        "port": 0,
        "timeout": 0
    },
    "quota_include_external_storage": false,
    "share_folder": "",
    "skeletondirectory": "\/srv\/nextclouddata\/presets\/",
    "theme": "",
    "trashbin_retention_obligation": "auto, 7",
    "updater.release.channel": "stable",
    "mail_smtpmode": "smtp",
    "mail_smtpauthtype": "LOGIN",
    "user_backends": [
        {
            "class": "\\OCA\\User_External\\WebDAVAuth",
            "arguments": [
                "***REMOVED SENSITIVE VALUE***"
            ]
        }
    ],
    "mail_from_address": "***REMOVED SENSITIVE VALUE***",
    "mail_domain": "***REMOVED SENSITIVE VALUE***",
    "mail_smtpauth": 1,
    "mail_smtpport": "465",
    "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
    "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
    "mail_smtpsecure": "ssl",
    "mail_smtphost": "***REMOVED SENSITIVE VALUE***"
}

Are you using external storage, if yes which one: webdav

Are you using encryption: false

Are you using an external user-backend, if yes which one: WebDAV

Client configuration

Browser: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:62.0) Gecko/20100101 Firefox/62.0

Operating system: Win 10

Logs

Browser log

not relevant

Nextcloud log

Browser log

not relevant

[violoncelloCH]

at least with WebDAV
e.g. the IMAP part handles this on it's own

[someone-somenet-org]

We are affected of this too... Whats the priority of this bug?