CVE-2025-6599

HIGH
7.5
CVSS Score
Published: November 18, 2025 at 01:19 AM UTC
Updated: October 18, 2026 at 08:10 PM UTC
63 products affected across 1 vendorEmg5523-t50b FirmwareEmg3525-t50b FirmwareVmg8623-t50b Firmware· also runs on 66 platforms

Using DX3301-T0 firmware by Zyxel?

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Severity
HIGH7.5
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 5.17\(abpc.6.1\)c0
zyxel-ax7501-b0 (same device)
v ≤ 5.17\(acbs.1.3\)c0
zyxel-dm4200-b0 (same device)
v ≤ 5.50\(abvy.6.3\)c0
zyxel-dx3300-t0 (same device)
v ≤ 5.50\(abvy.6.3\)c0
zyxel-dx3300-t1 (same device)
v ≤ 5.50\(abvy.6.3\)c0
zyxel-dx3301-t0 (same device)
v ≤ 5.17\(abyl.9\)c0
zyxel-dx4510-b1 (same device)
v ≤ 5.17\(abyo.7\)b2
zyxel-dx5401-b0 (same device)
v ≤ 5.17\(abyo.7\)b2
zyxel-dx5401-b1 (same device)
v ≤ 5.63\(acmu.1.1\)c0
zyxel-ee3301-00 (same device)
v ≤ 5.63\(acld.1.1\)c0
zyxel-ee5301-00 (same device)

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-400

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