Users of bitcoin exchanges and other online services are being warned to change their passwords in light of a newly discovered bug tied to web security firm Cloudflare.

Cloudflare, which provides denial-of-service protection, detailed the issue in a blog post published today. The company was first contacted about the bug last week by Google cybersecurity researcher Tavis Ormandy.

The so-called "Cloudbleed" bug – a reference to 2014's Heartbleed vulnerability –  is believed to have begun affecting services as early as September 2016, enabling the leak of memory that included sensitive information such as passwords and authentication tokens. The firm said the bug has since been patched.

News of the bug has triggered warnings from exchanges like Poloniex and Kraken, which suggested that users change their passwords, two-factor authentication and API keys. More broadly, cybersecurity advocates have strongly encouraged users of any site that utilizes Cloudflare to change their passwords as a precaution.

According to Cloudflare’s blog post, the real threat to users came as a result of some of that information being captured by search engines.

The firm explained:

A user on GitHub has curated a list of sites potentially affected by the bug, which includes industry services like Coinbase, BitPay, Blockchain and LocalBitcoins.

Other major websites, including Reddit, Uber and OKCupid, are said to be affected as well.

CoinDesk will continue monitoring this developing story.

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