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What are the security issues with AJAX?

The Ajax calls are sent in plain text format, this might lead to insecure database access. The data gets stored on the clients browser, thus making the data available to anyone. It also allows monitoring browsing sessions by inserting scripts.

AJAX function calls are sent in plain text to server. These calls may easily reveal database details, variable names etc 

User's browsing session can be monitored my maliciously inserting scripts

Ajax may encourage developers to use multiple server side pages thereby introducing multiple entry points for attackers