Missing ownership validation allows cross‑manager tracker–campaign linking

Summary

HackerOne community member hakuopi (and independently sy2no, garuthacktvist, and aszh) has reported a bypass of the fix for CVE‑2026‑34913. Proper ownership validation had not been applied to the reverse operation of linking campaigns and trackers through the tracker-campaigns.php script in Revive Adserver 6.0.7 and earlier. As a result, a low‑privileged user could link their trackers to campaigns owned by other managers on the same instance, leading to inconsistent ownership relationships.