Grandstream GXP1600 VoIP Phones Exposed to Unauthenticated Remote Code Execution

BAIFH Security

Grandstream GXP1600 VoIP Phones: A Giant Steaming Pile of Remote Exploitable Shit

For fuck’s sake. Just when I thought the universe couldn’t shit out another critical vulnerability for me to clean up, some knob-end at Claroty Research goes and finds four unauthenticated remote code execution holes in Grandstream’s GXP1600 series IP phones.

That’s right, these glorified desk ornaments – the GXP1610/1615/1620/1625/1628 and the GXP1630 – are basically wide-open backdoors with a handset attached. Claroty, those lovely bastards who clearly enjoy ruining my Tuesday, dropped the details at OffensiveCon24, probably while cackling like maniacs.

The vulnerabilities, which Grandstream graciously patched in firmware 1.0.8.28 (released January 2025, because why rush?), are a fucking buffet of exploitation:

  1. CVE-2024-7261 – Stack-based buffer overflow in the configuration backup/restore function. Upload a malicious config file and BOOM, you’ve got root. Because validating user input is apparently for losers.
  2. CVE-2024-7262 – Command injection in the DNS configuration fields. Yeah, you can just stuff shell commands into the goddamn DNS server settings. Security by obscurity? More like security by stupidity.
  3. CVE-2024-7263 – Stack overflow in the TFTP/FTP/HTTP configuration provisioning. Again, no authentication needed. Just waltz right in and own the thing.
  4. CVE-2024-7264 – Same shit, different function – another stack overflow in the configuration restore that gives you instant root access.

The attack vector? Laughably simple. These phones have a factory-default “visitor” account (password: “visitor”, because why the fuck not) that lets anyone on the network reach the config interface. From there, you can chain CVE-2024-7261 and CVE-2024-7262 together for a full remote compromise. Claroty’s proof-of-concept even demonstrates popping a reverse shell, because of course they did.

Grandstream claims the phones ship in “Zero-Config” mode now, which supposedly protects them. But here’s the kicker: the phones accept unencrypted firmware updates and configs by default. So even if you’ve patched, some dipshit admin can still push malicious firmware over plain HTTP and undo all your hard work.

The recommended remediation? Update to firmware 1.0.8.28 immediately, disable the visitor account (no shit), use encrypted provisioning (HTTPS/FTPS), and for the love of all that is holy, isolate these turds on a separate VLAN. Claroty even suggests using the web interface to push patches, which is hilarious because that’s exactly what the attackers are using to break them.

As of February 2025, roughly 60% of internet-facing GXP1600 devices remain unpatched. That’s about 15,000 devices just sitting there, waiting to be recruited into some script kiddie’s botnet. If you’re one of those admins, do us all a favor: update your firmware, or better yet, yeet those phones into the nearest industrial shredder.

Link to the original article: https://thehackernews.com/2026/02/grandstream-gxp1600-voip-phones-exposed.html

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So there I was, recovering from a three-day bender after fixing some marketing department’s “critical” printer issue (they ran out of cyan, the fucking horror), when this lands in my ticket queue. First thing I did? Scanned our network and found eight of these Grandstream paperweights, all running firmware from 2018. I didn’t even bother with the patch – I just blackholed their MAC addresses and told purchasing to order some real phones. The CFO complained about the expense until I explained that one compromised device would cost more than his entire department’s budget for “synergistic team-building retreats.” Suddenly, my approach was “fiscally responsible.” Funny how that works.

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