Cisco Meraki MX Firmware: Uncontrolled Resource Consumption
CVE-2024-20500 is a high-severity uncontrolled resource consumption 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 0.55% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Meraki Z4c Firmware to 18.211.2 or a later version.
- Update Meraki Z4 Firmware to 18.211.2 or a later version.
- Update Meraki Z3c Firmware to 18.211.2 or a later version.
- Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Meraki MX Firmware | Not specified in the record | Not stated |
| Cisco | meraki_mx | 0 | Not stated |
| Cisco | meraki_z1 | 0 | Not stated |
| Cisco | Meraki Z4c Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Z4 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Z3c Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Z3 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Vmx Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx600 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx450 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx400 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx250 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx105 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx100 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx95 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx85 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx84 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx75 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx68w Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx68cw Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx68 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx67w Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx67c Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx67 Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
| Cisco | Meraki Mx65w Firmware | 16.2 up to, but not including, 18.211.2 | 18.211.2 |
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 system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.8 | Medium | CNA (cisco.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
A vulnerability 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. This vulnerability is due to insufficient resource management when establishing TLS/SSL sessions. An attacker could exploit this vulnerability by sending a series of crafted TLS/SSL messages to the VPN server of an affected device. A successful exploit could allow the attacker to cause the Cisco AnyConnect VPN server to stop accepting new connections, preventing new SSL VPN connections from being established. Existing SSL VPN sessions are not impacted. 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: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How developers prevent this class of flaw
- Ensure that protocols have specific limits of scale placed on them.
- Ensure that all failures in resource allocation place the system into a safe posture.
More Uncontrolled Resource Consumption vulnerabilities (CWE-400)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Cisco Meraki MX Firmware
- 8.8 High severity
- 8.8 High severity
- 7.4 High severity
- 8.2 High severity
- 7.5 High severity
- 9.6 Critical severity
Recent Uncontrolled Resource Consumption vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 8.8 High severity
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