No, Signal has not been hacked. However, we do recommend turning off showing Signal content in notifications because the content is stored in memory on device. Apparently, this memory can be retrieved if an attacker has physical access to an unlocked device and has the right tool.

https://activistchecklist.org/signal/#signal-disable-notifications

Signal Security Checklist | Digital Security Checklists for Activists

Configure Signal to protect your messages and calls

Activist Checklist
@HasSignalBeenHacked uhm... if an attacker has access to the unlocked device...... why wouldn't he just open signal? (And no, I did actually not read the article, usually I do before asking stuff like that, but news like these have often bugged me in some CVE related disclosures as well.)

@jesterchen Yeah, that’s a great point. However, here’s an article in the news today that folks are talking about. Someone deleted the signal app but the notifications were still retrievable.

https://www.404media.co/fbi-extracts-suspects-deleted-signal-messages-saved-in-iphone-notification-database-2/

FBI Extracts Suspect’s Deleted Signal Messages Saved in iPhone Notification Database

The case was the first time authorities charged people for alleged “Antifa” activities after President Trump designated the umbrella term a terrorist organization.

404 Media

@HasSignalBeenHacked thanks for your reply. As I said: usually I read articles first,...

The new link is behind a paywall, but what I can see leads to new questions: Do people really believe, data is lost as soon as I delete something? And this is not even asking about other places where data might be stored. If I delete files, usually they're not physically deleted, only the allocation get's destroyed... and yeah, what typical user does know something like that, I know... (and that is long before clear vs. purge vs. cryptographically destroy like in NIST SP 800-88r2 or such).

And as long as the device is unlocked, the encryption won't help.......

And I know how difficult it is to explain the "basics" of this. So thanks again for the clarification.

@HasSignalBeenHacked And thanks for the list to the checklist above. I will share it. :)