Signed up for Klaviyo? Dozens of advertisers may have seen your password

A website bug at Klaviyo mistakenly shared users’ sign-up information with third-party companies, according to TechCrunch. The exposed information may have included personal data and passwords, and the report says dozens of advertisers may have been affected.

The incident directly touches Klaviyo’s handling of customer and prospect data. It raises the risk of customer remediation, scrutiny of privacy controls, and pressure on the company’s reputation with advertisers and other users.

Klaviyo’s FY 2025 revenue was $1.2B, up 31.6% YoY, with a 74.7% gross margin but a -2.6% net margin and $-0.11 diluted EPS. That growth profile is a concrete strength, but the negative bottom line leaves less evidence of a financial cushion if the incident creates additional costs or slows customer adoption.

The immediate setup is negative for the company-specific narrative, although the supplied data does not quantify the number of affected users, remediation costs, or any regulatory response. Those details, along with Klaviyo’s disclosure and customer-retention commentary, are the key next pieces of evidence.