blabbermouthed
blab·ber·mout·hed
adjective
1.
2.
prone to communicate confidential information
Origin
From blabber + mouthed.
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.