Well, we don't know for sure that an exploit exists for this bug on Android yet (the original exploit was for iOS via iMessage), but there's a reasonably high chance that one has been developed already. These types of exploits are in very high demand for Android right now, I've heard some eye-watering prices being mentioned recently.
Updating Chrome on an unsupported device would fix the issue, but you would still need an Android OS upgrade to fix the issue for apps like Signal and WhatsApp. Chrome bundles its own version of libwebp, but messaging apps and other highly exposed stuff like Gmail all use the OS provided interfaces for displaying images. Hopefully we'll start getting updates for security-supported Android devices in early October.
Updating Chrome on an unsupported device would fix the issue, but you would still need an Android OS upgrade to fix the issue for apps like Signal and WhatsApp. Chrome bundles its own version of libwebp, but messaging apps and other highly exposed stuff like Gmail all use the OS provided interfaces for displaying images. Hopefully we'll start getting updates for security-supported Android devices in early October.