Millions of consumers treat Weedmaps like the Yelp for pot, relying on the Irvine company as their definitive guide to marijuana dispensaries, varieties and doctors.

But a key feature — user reviews of pot businesses — may be tainted by thousands of potentially fraudulent comments, a flaw in the company’s software revealed.

Reviews on the site are pseudonymous, and visitors reasonably expect that each is written by a unique customer. But data that Weedmaps mistakenly leaked suggests a large proportion of a glowing remarks come from individual users leaving multiple reviews of a single business.

Of 598 businesses examined by the Los Angeles Times and a software developer, 70% had at least one batch of reviews originating from the same IP address.

The repetition is suspicious because IP addresses are typically associated with a single device for up to years. One address contributing several reviews for the same dispensary raises questions about their validity.

Weedmaps Media Inc. President Chris Beals disputed that his company’s user-generated ratings lead consumers...