An issue was discovered in Bloop Airmail 3 3.5.9 for macOS. Its primary WebView instance implements "webView:decidePolicyForNavigationAction:request:frame:decisionListener:" such that OpenURL is the default URL handler. A navigation request is processed by the default URL handler only if the currentEvent is NX_LMOUSEUP or NX_OMOUSEUP. An attacker may abuse HTML elements with an EventHandler for a chance to validate navigation requests for URLs that are processed during the NX_LMOUSEUP event triggered by clicking an email.

An issue was discovered in Bloop Airmail 3 3.5.9 for macOS. It registers and uses the airmail:// URL scheme. The "send" command in the URL scheme allows an external application to send arbitrary emails from an active account without authentication. The handler has no restriction on who can use its functionality. The handler can be invoked using any method that invokes the URL handler such as a hyperlink in an email. The user is not prompted when the handler processes the "send" command, thus leading to automatic transmission of an attacker crafted email from the target account.