Hackers are exploiting a critical command injection vulnerability in Zyxel CPE Series devices that has remained unpatched since last July.
GreyNoise is observing active exploitation attempts targeting a zero-day critical command injection vulnerability in Zyxel CPE Series devices tracked as CVE-2024-40891. At this time, the vulnerability is not patched, nor has it been publicly disclosed. Attackers can leverage this vulnerability to execute arbitrary commands on affected devices, leading to complete system compromise, data exfiltration, or network infiltration. At publication, Censys is reporting over 1,500 vulnerable devices online.
CVE-2024-40891 is very similar to CVE-2024-40890 (observed authentication attempts, observed command injection attempts), with the main difference being that the former is telnet-based while the latter is HTTP-based. Both vulnerabilities allow unauthenticated attackers to execute arbitrary commands using service accounts (supervisor and/or zyuser).
Martin Jartelius, CISO at Outpost24 had this to say:
“This is a case where the CVE system has not been efficient. As vendors withhold publishing information and CVEs until they have a solution, organizations are unable to proactively take action and remove critically vulnerable devices.”
“The vulnerability was put in a reserved state in July 2024 and has since remained undisclosed by the vendor, meaning that currently it is also not indexed by sources such as NVD. Many organizations source their vulnerability information from NVD, and even though security researchers and the vendor are aware, customers remain uninformed.”
“If we turn to the vendor and review the available drivers, they have a range of release dates, some dating as old as 2016, others released in spring 2024.”
“It should be noted that the devices are not present on either of the vendors lists of End-Of-Life devices, and the lack of updates addressing the issue is very concerning. Zyxel already prior to this constitutes several of the vulnerabilities listed in the CISA KEVs list, and if the latest two are added, Zyxel will on their own constitute 1% of the total list of Known Exploited Vulnerabilities.”
To say that this isn’t good is an understatement. Hopefully Zyxel decides to address this issue ASAP as the fact that this is being actively exploited isn’t going to end well for anyone using the Zyxel devices. Nor will it end well for Zyxel.





Microsoft 365 Services Had A Bit Of A Problem Yesterday
Posted in Commentary with tags Microsoft on January 30, 2025 by itnerdBleeping Computer is reporting that Microsoft had an issue that was preventing users and admins from accessing some Microsoft 365 services and the admin centre. There was a big spike yesterday afternoon in reports of trouble. But that seems to have reduced since then. Though I am still hearing of scattered issues today despite the fact that Microsoft’s status page listing everything as being fine. Thus I have to assume that these are just isolated incidents.
Jim Routh, Chief Trust Officer at cybersecurity company Saviynt, commented:
“When you’re a cybersecurity professional reading this update, you generally offer a sigh of relief since the outage is not related to a cyber security incident. The root cause is more of a rather mundane type of configuration change that caused the outage. There is always an opportunity to learn from these types of issues and the quick acknowledgement by Microsoft, along with their commitment to applying the lessons learned, is admirable for Microsoft customers.”
This outage appears to have been short in duration. But it highlights how dependant organizations are on Microsoft services. Hopefully Microsoft does all it can to make sure that whatever happened yesterday doesn’t happen again.
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