Linux was targeted, as it is a widely-proliferated operating system. However, it's large community and open-source development should help its developers address the vulnerabilities more easily than closed-source platforms.
Here's an official statement about Vault 7 from Nicko van Someren, Chief Technology Officer at The Linux Foundation:
While it is not surprising that Linux would find itself a target, the open source project has a very fast release cycle, meaning that kernel updates are released every few days to address issues that are found. Linux is an incredibly active open source project. Thousands of professional developers and volunteers - including many of the most talented in the world - are constantly contributing improvements and fixes to the project. This allows the kernel team to release updates every few days -- one of the fastest release cycles in the industry. Rapid release cycles enable the open source community to fix vulnerabilities and release those fixes to users faster.
He goes on to say:
Further, The Linux Foundation's Core Infrastructure Initiative (CII), which has the backing of many leading technology companies, is working to actively assist open source projects globally to help them develop their code using best practices proven to yield more secure results. Decades of software development tell us software will never be bug free. Through the work of open source communities, assistance from programs like CII and engagement with a vast pool of talent and support from contributing companies, we can enable open source software communities to continue producing some of the most secure software on the planet.
Anecdotally, what I mostly saw when I read about Vault 7 was Windows being targeted, along with Samsung phones and smart TVs. The moral of the story is, keep your systems updated and keep an eye on CVE bulletins, no matter what you are running.