Apple released iOS 17.3.1 on Thursday, about two weeks after the release of iOS 17.3. While the previous update brought new features, like Stolen Device Protection, to your iPhone, iOS 17.3.1 appears to be minor update that just patches a typing bug.
To download the update, go to Settings > General > Software Update, tap Install Now and follow the onscreen prompts.
Apple wrote in the update’s description only that it fixes an issue where text might duplicate or overlap while you’re typing. The company didn’t post common vulnerabilities and exposures, aka CVEs, for the update, so it’s unclear if iOS 17.3.1 addresses any security issues.
Apple normally posts an update’s CVEs online when the download becomes available. But there have been some instances when the company hasn’t posted CVEs, like with the release of iOS 17.2.1 and iOS 17.1.1.