I did some research and added some comments with an issue link:
Since the Activity will show whatever is in the comments you could search in that manner if you know there is a comment with that link but there isn't a search box per-se that you can search from.
I have not seen a feature request for this so I would also advise that you go to JAC and create a Suggestion request so we can get that feature added into JIRA. If you do create the Suggestion please post the link here so the Community can vote on it and add impact.
Badges are a great way to show off community activity, whether you’re a newbie or a Champion.Learn more
A picture tells a thousand words. And agility boards have just released their latest feature: cover images on issues – so now your board can tell a story at first glance. Upload attachmen...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs