CVE-2025-7673: Zyxel Vmg8825-t50k Firmware remote code execution (CVSS 9.8)

Description

A buffer overflow vulnerability in the URL parser of the zhttpd web server in Zyxel VMG8825-T50K firmware versions prior to V5.50(ABOM.5)C0 could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and potentially execute arbitrary code by sending a specially crafted HTTP request.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Zyxel Emg3525-t50b Firmware< 5.50\(absl.0\)b8 · < 5.50\(abpm.4\)c0

Zyxel Emg5523-t50b Firmware< 5.50\(absl.0\)b8 · < 5.50\(abpm.4\)c0

Zyxel Emg5723-t50k Firmware< 5.50\(abom.5\)c0

Zyxel Emg6726-b10a Firmware< 5.13\(abnp.6\).c

Zyxel Ex3510-b0 Firmware< 5.17\(abup.3\)c0

Zyxel Ex5510-b0 Firmware< 5.15\(abqx.3\)c0

Zyxel Vmg1312-t20b Firmware< 5.50\(absb.3\)c0

Zyxel Vmg3625-t50b Firmware< 5.50\(abpm.4\)c0

Zyxel Vmg3925-b10b Firmware< 5.13\(aavf.16\)c

Zyxel Vmg3925-b10c Firmware< 5.13\(aavf.16\)c

Zyxel Vmg3927-b50a Firmware< 5.15\(abmt.5\)c0

Zyxel Vmg3927-b50b Firmware< 5.13\(ably.6\)c0

Zyxel Vmg3927-b60a Firmware< 5.15\(abmt.5\)c0

Zyxel Vmg3927-t50k Firmware< 5.50\(abom.5\)c0

Zyxel Vmg4005-b50b Firmware< 5.13\(abrl.5\)c0

Zyxel Vmg4927-b50a Firmware< 5.13\(ably.6\)c0

Zyxel Vmg8623-t50b Firmware< 5.50\(abpm.4\)c0

Zyxel Vmg8825-b50a Firmware< 5.15\(abmt.5\)c0

Zyxel Vmg8825-b60a Firmware< 5.15\(abmt.5\)c0

Zyxel Vmg8825-bx0b Firmware< 5.17\(abny.5\)c0

Zyxel Vmg8825-t50k Firmware< 5.50\(abom.5\)c0

Zyxel Vmg8924-b10d Firmware< 5.13\(abgq.6\)c0

Zyxel Xmg3927-b50a Firmware< 5.15\(abmt.5\)c0

Zyxel Xmg8825-b50a Firmware< 5.17\(abmt.5\)c0

Remediation

Fixed in

Zyxel Emg3525-t50b Firmware≥ 5.50\(absl.0\)b8

Zyxel Emg5523-t50b Firmware≥ 5.50\(absl.0\)b8

Zyxel Emg5723-t50k Firmware≥ 5.50\(abom.5\)c0

Zyxel Emg6726-b10a Firmware≥ 5.13\(abnp.6\).c

Zyxel Ex3510-b0 Firmware≥ 5.17\(abup.3\)c0

Zyxel Ex5510-b0 Firmware≥ 5.15\(abqx.3\)c0

Zyxel Vmg1312-t20b Firmware≥ 5.50\(absb.3\)c0

Zyxel Vmg3625-t50b Firmware≥ 5.50\(abpm.4\)c0

Zyxel Vmg3925-b10b Firmware≥ 5.13\(aavf.16\)c

Zyxel Vmg3925-b10c Firmware≥ 5.13\(aavf.16\)c

Patch & vendor advisories

https://www.zyxel.com/service-provider/global/en/zyxel-security-advisory-remote-code-execution-and-denial-service-vulnerabilities-cpe

References

https://www.zyxel.com/service-provider/global/en/zyxel-security-advisory-remote-code-execution-and-denial-service-vulnerabilities-cpeVendor Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2025-7673 being actively exploited?

CVE-2025-7673 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.59%.

How severe is CVE-2025-7673?

CVE-2025-7673 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.59% probability of exploitation.

Which products are affected by CVE-2025-7673?

Affected products include Zyxel Emg3525-t50b Firmware, Zyxel Emg5523-t50b Firmware, Zyxel Emg5723-t50k Firmware, Zyxel Emg6726-b10a Firmware, Zyxel Ex3510-b0 Firmware, and 19 more.

How do I fix CVE-2025-7673?

Upgrade affected software to a fixed version, for example Zyxel Emg3525-t50b Firmware 5.50\(absl.0\)b8, Zyxel Emg5523-t50b Firmware 5.50\(absl.0\)b8, Zyxel Emg5723-t50k Firmware 5.50\(abom.5\)c0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-7673 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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