In agent/Core/SpawningKit/Spawner.h in Phusion Passenger 5.1.10 (fixed in Passenger Open Source 5.1.11 and Passenger Enterprise 5.1.10), if Passenger is running as root, it is possible to list the contents of arbitrary files on a system by symlinking a file named REVISION from the application root folder to a file of choice and querying passenger-status --show=xml.
{ "vanir_signatures": [ { "target": { "file": "src/agent/Core/SpawningKit/Spawner.h" }, "id": "CVE-2017-16355-bb6469dd", "signature_version": "v1", "digest": { "line_hashes": [ "268799682548938772947881921096668350310", "117681501307321166777979843663423129027", "280083727406545110470011300718420250903", "222560687676110990119119317121042802472", "235854114548696804817144001729705555967", "83449442481079981626893397623410921398", "320115127452501949654491876132754416636", "207948168575058203827937063282176268874", "327753644294967020574950308097127961444", "130370208306564958597886905471594157991", "55551024395305749768445773965125912360" ], "threshold": 0.9 }, "source": "https://github.com/phusion/passenger/commit/4043718264095cde6623c2cbe8c644541036d7bf", "deprecated": false, "signature_type": "Line" } ] }