Lychee is a free, open-source photo-management tool. Prior to 7.6.1, when photos_star_visibility is set to anonymous, POST /api/v2/Photo::highlight can fetch and modify a photo without confirming that the caller can see it. BaseApiRequest::validateResolved() invokes SetPhotosHighlightedRequest::processValidatedValues() before authorization, and PhotoPolicy::canHighlight() returns true for anonymous callers without a canSee check. An unauthenticated attacker who can guess photo identifiers can distinguish existing private photos through differing success and not-found responses and can change t