Hackers exploited a vulnerability in CoinMarketCap’s front-end system, using a seemingly harmless doodle image to inject malicious code that triggered fake wallet verification pop-ups across the site.
The breach, confirmed by CoinMarketCap, used its backend API to deliver a manipulated JSON payload that embedded JavaScript into the homepage according to blockchain security firm Coinspect Security.
On June 20, 2025, our security team identified a vulnerability related to a doodle image displayed on our homepage. This doodle image contained a link that triggered malicious code through an API call, resulting in an unexpected pop-up for some users when visited our homepage.…
— CoinMarketCap (@CoinMarketCap) June 21, 2025
The script caused an unauthorized prompt instructing users to “Verify Wallet,” a phishing tactic aimed at tricking visitors into handing over access to their crypto holdings.
The blockchain security firm traced the attack to the platform’s rotating “doodles” feature, which allowed attackers to embed the malicious code without altering the site’s core infrastructure.
The pop-up was live for a short period before being removed by CoinMarketCap’s team.
“Upon discovery, we acted immediately to remove the problematic content,” CoinMarketCap said in a statement posted to social media. “Comprehensive measures have been implemented to isolate and mitigate the issue.”
CoinMarketCap has not disclosed how many users encountered the pop-up or whether any wallets were compromised.
