Zyxel GS1900-24E switch flaw exploited as zero-day
An unauthenticated out-of-bounds write in Zyxel GS1900-24E switch firmware allows remote command execution, reportedly exploited as a zero-day.
Sourceadvisories.ncsc.nl — open the original
What to check
- Applies to
- The 1 CVE named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- No exploitation in the wild and no public exploit is recorded for the CVEs named.
NCSC-NL published an advisory for a vulnerability in the Zyxel GS1900-24E network switch, affecting firmware version 2.90(AAHK.2)C0 and earlier. The flaw, tracked as CVE-2026-107441 (CVSS v3 8.8), is an out-of-bounds write in the CGI component of the device's management interface, caused by insufficient bounds checking. An unauthenticated attacker with access to the management interface can send specially crafted HTTP requests to execute arbitrary commands on the device.
According to public news reports, the vulnerability has been actively exploited as a zero-day, though NCSC-NL states it has not yet independently verified this claim. Zyxel has released firmware updates to address the issue. NCSC-NL recommends placing management interfaces on a separate network segment and ensuring they are not directly reachable from the internet, a standard mitigation that also reduces exposure to this flaw.
Defenders using affected GS1900-24E switches should prioritize applying the Zyxel firmware update and verify that management interfaces are not internet-facing. Given the reported active exploitation and the low barrier to exploit (no authentication required), this should be treated as a priority patching item for any exposed devices.
Mentioned in this report
Source reporting: https://advisories.ncsc.nl/2026/ncsc-2026-0468.html
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