Improper Cache Validation vulnerability in the SoupCache implementation of the libsoup HTTP library.The flaw is due to libsoup ignoring the HTTP Vary header when determining whether a cached response is valid for subsequent requests. This oversight occurs in the soup_cache_has_response() function, where an unimplemented check results in cached responses being reused incorrectly across different request contexts. If exploited, an attacker could cause highly sensitive or user-specific content to be served to unintended recipients, resulting in serious information disclosure. The issue is only relevant to applications that explicitly enable SoupCache, and exploitation is more plausible in proxy-like scenarios rather than standard GNOME desktop use cases.