Contax/Yashica mount lenses can be adapted to Sony E-mount (not A-mount) and Panasonic/Olympus micro four-thirds and other mirrorless cameras, as well as Canon EOS-mount dSLRs. They cannot be adapted to Nikon F mount dSLRs with simple rings because of the flange distance issues, but you might be able to replace the mount with a Leitax kit; however the cost will probably make just getting a native 18-55 kit lens more practical. However, be aware you won't have aperture control from the camera, autofocus, you'll have to use stop-down metering, and there won't be any EXIF information from the lens. (See: Can I use lens brand X on interchangeable lens camera brand Y?)
Strangely, you're more restricted on the Canon EOS lens. Canon's EOS (EF) lenses can be used directly on their dSLRs, but adapting one to another brand of camera is more than problematic, because EOS lenses have no aperture ring, and without electronic communication, you have no control over aperture. In this case, mirrorless mounts are only mounts you can adapt to with an expensive Metabones adapter that can "translate" the electronic signals between the body and the lens and allow for aperture control. But again, the cost may simply make going for a native equivalent lens more practical.
Personally, neither of those lenses is really worth the pain to adapting. They've got relatively small ranges, and slow max. apertures, and aren't a great fit for general walkaround use on a camera with an APS-C sensor (i.e., most mirrorless and entry-level dSLRs). An 18-55 kit lens is, on APS-C, a 28-80mm f/3.5-5.6 equivalent, and serves the same purpose your two lenses did on their respective bodies, and is really cheap if it comes with the kit.