Read Twitter CEO Agrawal’s Memo About the Whistle-Blower (1)

Twitter Inc. Chief Executive Officer Parag Agrawal defended the company Tuesday in an email to employees after a former executive claimed the social network ignored major security vulnerabilities and doesn’t know how many spam bots it has on the platform.

Peiter “Mudge” Zatko, the former top security executive at Twitter, filed the whistle-blower complaint with Congress and regulatory agencies. Tesla Inc. CEO Elon Musk’s lawyers are already seeking more information in an effort to help Musk get out of a $44 billion Twitter acquisition deal he signed in April.

Twitter disputed the claims Tuesday, adding that Zatko was fired ...