CVE-2025-8679

Unauthenticated network access via repeated captive-portal logins

Published Oct 1, 2025 · Updated Oct 1, 2025

Authentication bypass in Extreme Networks ExtremeGuest Essentials before 25.5.0 allows remote attackers to obtain network access. Under certain captive-portal SSID configurations, repeated manual login attempts cause an unauthenticated device to be marked as authenticated; Client360 can log its MAC address as the username even when MAC authentication is disabled. Reachability requires access to the configured guest SSID, and successful exploitation grants that device network connectivity without portal authentication.

CVSS severity7.6
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Extreme Networks ExtremeGuest Essentials before 25.5.0 allows remote attackers to obtain network access. Under certain captive-portal SSID configurations, repeated manual login attempts cause an unauthenticated device to be marked as authenticated; Client360 can log its MAC address as the username even when MAC authentication is disabled. Reachability requires access to the configured guest SSID, and successful exploitation grants that device network connectivity without portal authentication.

The record

CVE
CVE-2025-8679
Published
Oct 1, 2025
Updated
Oct 1, 2025
Vendor
Extreme Networks
Product
ExtremeGuest Essentials
Classifications
CWE-307, T1110
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 1, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=25.4.0

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Extreme Networks · ExtremeGuest Essentialsversion=25.4.0

Published CVSS scores

7.6Extreme NetworksCVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
T1110Brute Force

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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