CyberSecBulletin
CVE-2024-20498NVD status: Modified

Cisco Meraki MX Firmware: Double Free

Published Updated By the CyberSecBulletin desk

CVE-2024-20498 is a high-severity double free vulnerability in Cisco Meraki MX Firmware from Cisco, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.51% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Meraki Mx65 Firmware to 18.211.2 or a later version.
  2. Update Meraki Mx64 Firmware to 18.211.2 or a later version.
  3. Update Meraki Z4c Firmware to 18.211.2 or a later version.
  4. Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
  5. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
CiscoCisco Meraki MX FirmwareNot specified in the recordNot stated
Ciscomeraki_mx0Not stated
Ciscomeraki_z10Not stated
CiscoMeraki Mx65 Firmware17.6.0 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx64 Firmware17.6.0 up to, but not including, 18.211.218.211.2
CiscoMeraki Z4c Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Z4 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Z3c Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Z3 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Vmx Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx600 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx450 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx400 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx250 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx105 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx100 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx95 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx85 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx84 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx75 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx68w Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx68cw Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx68 Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx67w Firmware16.2 up to, but not including, 18.211.218.211.2
CiscoMeraki Mx67c Firmware16.2 up to, but not including, 18.211.218.211.2

Version data comes from the organisation that assigned the CVE; 3 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.6HighCNA (cisco.com)
CVSS 3.17.5HighNVD

Official description

Multiple vulnerabilities in the Cisco AnyConnect VPN server of Cisco Meraki MX and Cisco Meraki Z Series Teleworker Gateway devices could allow an unauthenticated, remote attacker to cause a DoS condition in the AnyConnect service on an affected device. These vulnerabilities are due to insufficient validation of client-supplied parameters while establishing an SSL VPN session. An attacker could exploit these vulnerabilities by sending a crafted HTTPS request to the VPN server of an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to restart, resulting in the failure of the established SSL VPN connections and forcing remote users to initiate a new VPN connection and reauthenticate. A sustained attack could prevent new SSL VPN connections from being established. Note: When the attack traffic stops, the Cisco AnyConnect VPN server recovers gracefully without requiring manual intervention.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Double Free

The product calls free() twice on the same memory address.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
  • Use a static analysis tool to find double free instances.

More Double Free vulnerabilities (CWE-415)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Cisco Meraki MX Firmware

All Cisco Meraki MX Firmware vulnerabilities

Recent Double Free vulnerabilities

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