Tumblr has admitted that Apple suddenly pulled its app from the iOS App Store due to the discovery of child porn which slipped past the site's filters, after Download presented their findings to the company.

The Yahoo!-owned social media network issued a statement, saying that they have a zero tolerance policy when it comes to child sexual exploitation and abuse, and that "Every image uploaded to Tumblr is scanned against an industry database of known child sexual abuse material, and images that are detected never reach the platform."

The company admits that "a routine audit discovered content on our platform that had not yet been included in the industry database. We immediately removed this content. Content safeguards are a challenging aspect of operating scaled platforms. We're continuously assessing further steps we can take to improve and there is no higher priority for our team."

Tumblr is a bastion for NSFW content - which resulted in its brief ban in Indonesia. Child porn, however, is a different matter.

This isn't the first time Tumblr has run into this type of problem. In March 2018, the Indonesian government briefly blocked Tumblr over the company's failure to remove pornographic content from its service. In 2017, South Korea asked Tumblr to take down certain pornographic content. The company initially rejected that request but eventually promised to better monitor the spread of adult content. -Download

A spokesman for the National Center for Missing and Exploited Children explained their reporting database to Download.

The National Center for Missing & Exploited Children operates the CyberTipline, which serves as the nation's centralized reporting system for online child sexual exploitation. Members of the public and Electronic Service Providers (ESPs) report instances of online child sexual exploitation to the CyberTipline. Last year, NCMEC received more than 10 million reports to its CyberTipline with the vast majority of those reports submitted by ESPs. NCMEC recognizes that global efforts to reduce the proliferation of online child sexual exploitation online requires an industry-wide effort and applauds all ESPs that engage in voluntary efforts to provide content safeguards for their users. In addition to receiving reports from ESPs, any member of the public who comes across suspected child abuse imagery is encouraged to make a CyberTipline report to NCMEC. -Download

Tumblr's removal from the iOS App Store was first noticed by PiunikaWeb, which reported that those with iOS parental controls enabled were unable to find the app. A short while later, the app vanished altogether.

Tumblr's help center site noted the disappearance in a statement: "We're working to resolve an issue with the iOS app and hope to be fully functional again soon. We really appreciate your patience as we figure this out, and we'll update this article when we have news to share," the company said. Through November 18, the company's message on its help center was that its team was still working on the issue with the app. After this article was first published on November 19, Tumblr updated it to include the statement above that its spokesperson presented to Download.com. -Download

iOS users who have previously downloaded the Tumblr app can re-download it if necessary by checking the purchase history on their device. First time users will need to wait until the app is reinstated. It remains available at Google Play, meanwhile, for Android users.