How severe is CVE-2025-6599?

CVE-2025-6599 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2025-6599 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-6599?

CVE-2025-6599 primarily affects Zyxel Lte3301-plus Firmware. In total, 66 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-6599?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-6599 have an EU (EUVD) identifier?

Yes. CVE-2025-6599 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-197903.

When was CVE-2025-6599 published?

CVE-2025-6599 was published on 2025-11-18 and last updated on 2026-06-17.

CVE-2025-6599

CVE-2025-6599 is a medium-severity vulnerability in Zyxel Lte3301-plus Firmware with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-197903
Weakness: CWE-400
Affected product: Zyxel Lte3301-plus Firmware
Published: 2025-11-18
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2025-6599?: 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.
How severe is CVE-2025-6599?: CVE-2025-6599 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2025-6599 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-6599?: CVE-2025-6599 primarily affects Zyxel Lte3301-plus Firmware. In total, 66 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-6599?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-6599 have an EU (EUVD) identifier?: Yes. CVE-2025-6599 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-197903.
When was CVE-2025-6599 published?: CVE-2025-6599 was published on 2025-11-18 and last updated on 2026-06-17.

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

Affected products (66)

cpe:2.3:o:zyxel:lte3301-plus_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nr5103_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nr5103e_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nr5309_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nr7302_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nr7303_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nebula_fwa505_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nebula_fwa510_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nebula_fwa515_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nebula_fwa710_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:dm4200-b0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:dx3300-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:dx3300-t1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:dx3301-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:dx4510-b1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:dx5401-b0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:dx5401-b1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ee3301-00_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ee5301-00_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ee6510-10_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex3300-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex3300-t1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex3301-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex3500-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex3501-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex3600-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex5401-b0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex5401-b1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex5501-b0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex5510-b0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex5512-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex5601-t0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex5601-t1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex7501-b0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:ex7710-b0_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:emg3525-t50b_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:emg5523-t50b_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:emg5723-t50k_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:emg6726-b10a_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:gm4100-b0_firmware:*:*:*:*:*:*:*:*

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