TYPO3 Core

If you installed more than one typo3 instance on same domain, the user session cookie will invaild and overwrite eachother.

Solution: apply typo3 site path into cookie
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if (($this->newSessionID || $this->forceSetCookie) && $this->lifetime==0 ) {
if (!$this->dontSetCookie) {
//SetCookie($this->name, $id, 0, '/');
$folder=substr(t3lib_div::getIndpEnv('TYPO3_SITE_URL'),strlen(t3lib_div::getIndpEnv('TYPO3_REQUEST_HOST')));;
SetCookie($this->name, $id, 0, $folder);
if ($this->writeDevLog) t3lib_div::devLog('Set new Cookie: '.$id, 't3lib_userAuth');
}
}

// If it is NOT a session-cookie, we need to refresh it.
        if ($this->lifetime > 0) {
            if (!$this->dontSetCookie)    {
                //SetCookie($this->name, $id, time()+$this->lifetime, '/');
                $folder=substr(t3lib_div::getIndpEnv('TYPO3_SITE_URL'),strlen(t3lib_div::getIndpEnv('TYPO3_REQUEST_HOST')));;
                SetCookie($this->name, $id, 0, $folder);
                if ($this->writeDevLog)     t3lib_div::devLog('Update Cookie: '.$id, 't3lib_userAuth');
            }
        }

(issue imported from #M2078)