CVE-2024-20500Network attack vector

New VPN connection denial via TLS resource exhaustion

Published Oct 2, 2024 · Updated Jun 4, 2025

Resource exhaustion in Cisco AnyConnect VPN on Meraki MX and Z Series firmware allows remote attackers to block new SSL VPN connections. The server insufficiently manages resources while establishing TLS/SSL sessions, so crafted messages exhaust capacity for new sessions. Exposure requires AnyConnect VPN to be enabled; existing sessions remain intact, and acceptance resumes after the traffic stops.

CVSS severity5.8
Medium
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Cisco AnyConnect VPN on Meraki MX and Z Series firmware allows remote attackers to block new SSL VPN connections. The server insufficiently manages resources while establishing TLS/SSL sessions, so crafted messages exhaust capacity for new sessions. Exposure requires AnyConnect VPN to be enabled; existing sessions remain intact, and acceptance resumes after the traffic stops.

The record

CVE
CVE-2024-20500
Published
Oct 2, 2024
Updated
Jun 4, 2025
Vendor
ClamAV
Product
Cisco Meraki MX Firmware
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 2, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 4, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0
  2. Affected versionversion=N/A

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Meraki MX Firmwareversion=0; version=N/A
ClamAV · Cisco Meraki Z1 Firmwareversion=0

Published CVSS scores

5.8CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

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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