Researchers Find 84 Flaws in the Guts of 4G and 5G Networks

Key points

• Researchers at Nanyang Technological University in Singapore disclosed 84 vulnerabilities affecting 4G and 5G core networks.
• The flaws could allow denial-of-service attacks, meaning the network is knocked offline for users.
• One flaw could enable session hijacking, letting an attacker take over a user's live connection.
• The bugs sit in the core software that carriers run, not in phones or SIM cards.
• No active exploitation has been reported so far.

A team of academic researchers has uncovered 84 security flaws in the software that runs modern mobile networks, weaknesses that could let attackers cut users off or, in the worst case, hijack their live phone sessions.

The research comes from Nanyang Technological University in Singapore. It was first reported by The Hacker News.

The flaws sit inside what the industry calls the "core network": the back-end computers a carrier operates to route calls, texts and mobile data. Your phone talks to a cell tower. The tower talks to the core. If the core misbehaves, so does everything on top of it.

What can attackers actually do with these bugs?

Two things, mainly. They can trigger a denial-of-service, which means flooding or crashing a system so real users cannot get through, knocking service offline for anyone connected. And in some cases they can hijack a user's session, taking over the live link between a phone and the network as if they were the legitimate owner.

A denial-of-service attack against a mobile core is not a minor inconvenience. Emergency calls, payment terminals, connected cars and hospital devices all ride on the same infrastructure.

Session hijacking is the more alarming scenario. If an attacker seizes a user's session, they could potentially intercept traffic tied to that account or impersonate the subscriber on the network.

Who is at risk?

Mobile carriers, not consumers directly. The vulnerabilities live in equipment operated by network providers. Ordinary customers cannot patch a mobile core from their handset.

That said, if a carrier's core is attacked, its customers feel the effects: dropped service, failed calls, or, in a hijack scenario, exposure of their traffic.

How were the flaws found?

The Singapore team studied the protocols and software that carriers use to run their cores, then probed for weaknesses that could be triggered from within the network. The researchers describe the problems as a "widespread class" of issues, meaning the same underlying design mistakes crop up across multiple products from multiple vendors.

That framing matters. It is not one buggy box from one supplier. It is a pattern.

Is this being exploited right now?

No public evidence of exploitation has surfaced. The disclosure is a research finding, not an incident report. Vendors and carriers now have to work through the list, confirm which of their products are affected, and issue fixes.

History says patching mobile core equipment is slow. Carriers test heavily before touching production systems, because a bad update can drop service for millions of subscribers.

What should ordinary customers do?

Nothing on your phone will fix this. There is no app update, no setting to toggle. The responsibility sits with carriers and equipment vendors.

If your mobile service drops in a way that feels unusual, that is worth reporting to your provider, but the far more likely cause is still an everyday outage. Keep an eye on statements from your carrier over the coming weeks as vendors publish advisories.

For security teams at telecoms, the practical work starts now: inventory core network components, watch vendor bulletins, and prioritise segments handling authentication and session management.