Web cache poisoning
Summary: PortSwigger Research describes web cache poisoning, which arises when an application behind a cache processes input that is not part of the cache key, so two requests the cache treats as equivalent can produce different responses. An attacker sends crafted input that triggers a harmful response the cache then stores and serves to other users, with impact depending on what the input achieves, often XSS or a redirect to another domain.
Bottom line: The malicious cached page can be served to a large number of users without any further interaction, so a single crafted request can turn one poisoned cache entry into a problem for everyone who requests that page.
Read the original at PortSwigger Research ↗
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