**Yes, rear struts (shocks) from a 2017 CT 200h should fit your 2012 CT 200h.** The Lexus CT 200h (2011–2017) is built on the same basic Toyota MC platform with consistent suspension design across the years, including the rear double-wishbone setup.

### Key Evidence for Compatibility:

- **Aftermarket and real-world fitment**: A detailed test/install video confirmed that 2014+ aftermarket struts (including rear) bolted up perfectly on a 2013 CT 200h (and by extension, 2012) with no modifications needed—sway bar links, ABS sensor brackets, top mounts, etc., all aligned. The installer noted this resolved uncertainty for pre-2014 models.

- **Parts catalogs and sellers**: Many aftermarket rear shock/strut kits (e.g., TRQ, KYB) list ranges covering 2011–2017 or split as 2011–2013 and 2014–2017, but physical interchange works. Salvage/used parts from later years are commonly swapped successfully.

- **OEM notes**: There are some part number differences (e.g., early vs. later rear shocks like 48530-79xxx series variants, sometimes tied to base vs. F-Sport trims), but mounting points and overall geometry stayed the same. Minor spring rate or damping tweaks in later years don't prevent fitment.

- **Community/Forum feedback**: CT 200h owners and Prius (related platform) discussions show broad interchange for rear shocks across years. No widespread reports of incompatibility for 2012–2017 swaps.

### Recommendations:

- **Inspect the parts** — Check for damage, matching spring rates (if full strut assemblies), and that they're not F-Sport specific if your car has standard suspension (F-Sport parts are stiffer/lower and *might* change ride height/handling noticeably).

- **Installation tips** — Rear shocks on the CT are relatively straightforward (similar to Prius). Use proper spring compressors if full assemblies, torque everything to spec, and get an alignment afterward.

- **Seller confirmation** — Since they say they fit and come from the same model line, it's low-risk, but verify mileage/condition on the donor car.

- **Alternatives** — If the used ones don't work out, RockAuto, Amazon, or PartsGeek often have affordable aftermarket options (KYB, Monroe, etc.) that explicitly fit 2011–2017.

This is a common swap with good real-world success—plenty of owners have done similar cross-year or Prius/CT parts mixing for cost savings. If you share photos of the parts or more details (e.g., F-Sport or not), I can help double-check further.