Antivirus or web protection blocks mail.mil and other CAC sites
windowsmacos
Symptoms
CAC sites (most commonly webmail) fail to load, hang, or strip out the CAC prompt; disabling the antivirus temporarily makes the site work.
Likely cause
Modern antivirus suites perform HTTPS interception (TLS man-in-the-middle scanning). That breaks client-certificate authentication because the AV terminates the TLS session before the CAC certificate can be presented.
Fix
Add 'https://*.mail.mil' (and any other failing DoD URL) to the trusted-sites / exclusion list of your antivirus, then turn off HTTPS / encrypted scanning. Product-specific paths:
- Avast: Settings > General > Exclusions > add *mail.mil. Also turn off Web Shield while testing.
- AVG: Add https://*.mail.mil to the exceptions list.
- Bitdefender: Protection > Settings > Online Threat Prevention > turn off 'Encrypted web scan'.
- Cisco AnyConnect (Mac): uninstall the 'Cisco Umbrella Plugin'.
- Covenant Eyes: uninstall and call 877-479-1119.
- ESET: add the sites to the exclusion list per ESET KB2960.
- Kaspersky: Settings > Additional > Network > set 'Encrypted connections scanning' to 'Do not scan'; uncheck 'Inject script into web traffic'; turn off Parental Controls.
- McAfee: add https://*.mail.mil to allowed sites; for stubborn issues, uninstall using the McAfee removal tool.
- Malwarebytes: Settings > Protection > Advanced > uncheck 'Disable Internet Explorer VB Scripting'.
- NordVPN: turn off Threat Protection > Web Protection.
- Qustodio / McAfee Safe Family: uninstall (parental controls cannot be configured around CAC).
- Total Defense: gear shield > Web Protection > turn off 'Scan Secured Websites'.
- Windows Defender SmartScreen: Internet Options > Advanced > turn off SmartScreen.
Sourced from militarycac.com. Rewritten for clarity.
Didn't work, or need it tailored to your setup?
Ask the AI assistant