CVE-2024-39345: AdTran 834-5 HDC17600021F1 (SmartOS 11.1.1.1) devices enable the SSH service by default and have a hidden, undocumented, hard-coded support account whose passwo

AdTran 834-5 HDC17600021F1 (SmartOS 11.1.1.1) devices enable the SSH service by default and have a hidden, undocumented, hard-coded support account whose passwo

AdTran 834-5 HDC17600021F1 (SmartOS 11.1.1.1) devices enable the SSH service by default and have a hidden, undocumented, hard-coded support account whose password is based on the devices MAC address. All of the devices internet interfaces share a similar MAC address that only varies in their final octet. This allows network-adjacent attackers to derive the support user's SSH password by decrementing the final octet of the connected gateway address or via the BSSID. An attacker can then execute arbitrary OS commands with root-level privileges. NOTE: The vendor states that there is no intended functionality allowing an attacker to execute arbitrary OS Commands with root-level privileges. The vendor also states that this issue was fixed in SmartOS 12.5.5.1.

Description from the National Vulnerability Database, published by MITRE

What it means for a small business

If your business uses 834-5_firmware, install the vendor's update. If you're not sure whether you use it, ask whoever manages your computers.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.53%, higher than 44% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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