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.
Conclusion & alert: CVE-2018-15670 is rated Low Risk (35/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.74%).Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
Exploit prediction scoring system (EPSS) score for CVE-2018-15670
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).