CVE-2026-57439: CyberChef: Prototype pollution in Series Chart operation

On 5 June 2026 CyberChef received a security vulnerability report from @hyuunnn detailing a vulnerability in the Series Chart operation, where malicious input could result in prototype pollution of the data structures outputted from the operation. Other operations following Series Chart could have their behaviour manipulated by the attacker-controlled prototype, for example, injecting malicious content into their HTML output.

In this case, a demonstration was provided that chained the Series Chart operation with the Parse UDP operation to cause attacker controlled JavaScript to be executed.