CVE-2025-6599

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-11-18 · updated 2026-10-18
Weakness: CWE-400

Description

An uncontrolled resource consumption vulnerability in the web server of Zyxel DX3301-T0 firmware version 5.50(ABVY.6.3)C0 and earlier could allow an attacker to perform Slowloris‑style denial‑of‑service (DoS) attacks. Such attacks may temporarily block legitimate HTTP requests and partially disrupt access to the web management interface, while other networking services remain unaffected.

Affected products

Zyxel AX7501-B0 firmware: through 5.17\(abpc.6.1\)c0
Zyxel AX7501-B1 firmware: through 5.17\(abpc.6.1\)c0
Zyxel Dm4200-B0 Firmware: through 5.17\(acbs.1.3\)c0
Zyxel DX3300-T0 firmware: through 5.50\(abvy.6.3\)c0
Zyxel DX3300-T1 firmware: through 5.50\(abvy.6.3\)c0
Zyxel DX3301-T0 firmware: through 5.50\(abvy.6.3\)c0
Zyxel Dx4510-B1 Firmware: through 5.17\(abyl.9\)c0
Zyxel DX5401-B0 firmware: through 5.17\(abyo.7\)b2
Zyxel Dx5401-B1 Firmware: through 5.17\(abyo.7\)b2
Zyxel Ee3301-00 Firmware: through 5.63\(acmu.1.1\)c0
Zyxel Ee5301-00 Firmware: through 5.63\(acld.1.1\)c0
Zyxel Ee6510-10 Firmware: through 5.19\(acjq.3\)c0
Zyxel Emg3525-T50B Firmware: through 5.50\(abpm.9.5\)c0
Zyxel Emg5523-T50B Firmware: through 5.50\(abpm.9.5\)c0
Zyxel Emg5723-T50K Firmware: through 5.50\(abom.8.6\)c0
Zyxel Emg6726-B10A Firmware: through 5.13\(abnp.8\)c0
Zyxel Ex3300-T0 Firmware: through 5.50\(abvy.6.3\)c0; through 5.50\(acdi.2.1\)c0
Zyxel Ex3300-T1 Firmware: through 5.50\(abvy.6.3\)c0
Zyxel EX3301-T0 firmware: through 5.50\(abvy.6.3\)c0
Zyxel Ex3500-T0 Firmware: through 5.44\(achr.4\)c0
Zyxel EX3501-T0 firmware: through 5.44\(achr.4\)c0
Zyxel Ex3600-T0 Firmware: through 5.70\(acif.1.2\)c0
Zyxel Ex5401-B0 Firmware: through 5.17\(abyo.7\)b2
Zyxel Ex5401-B1 Firmware: through 5.17\(abyo.7\)b2
Zyxel Ex5501-B0 Firmware: through 5.17\(abry.5.5\)c0
Zyxel Ex5510-B0 Firmware: through 5.17\(abqx.10\)c0
Zyxel Ex5512-T0 Firmware: through 5.70\(aceg.5\)c0
Zyxel Ex5601-T0 Firmware: through 5.70\(acdz.4.1\)c0
Zyxel EX5601-T1 firmware: through 5.70\(acdz.4.1\)c0
Zyxel Ex7501-B0 Firmware: through 5.18\(achn.2.1\)c0

References

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-uncontrolled-resource-consumption-and-command-injection-vulnerabilities-in-certain-4g-lte-5g-nr-cpe-dsl-ethernet-cpe-fiber-onts-security-routers-and-wireless-extenders-11-18-2025

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