CVE-2024-20509

02.10.2024, 19:15

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 hijack an AnyConnect VPN session or cause a denial of service (DoS) condition for individual users of the AnyConnect VPN service on an affected device.

This vulnerability is due to weak entropy for handlers that are used during the VPN authentication process as well as a race condition that exists in the same process. An attacker could exploit this vulnerability by correctly guessing an authentication handler and then sending crafted HTTPS requests to an affected device. A successful exploit could allow the attacker to take over the AnyConnect VPN session from a target user or prevent the target user from establishing an AnyConnect VPN session with the affected device.

Race Condition

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
NIST	NIST	5.8 MEDIUM	NETWORK	LOW	NONE	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
cisco	CNA	5.8 MEDIUM	NETWORK	LOW	NONE	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
CISA-ADP	ADP	---				---

Base Score

CVSS 3.x

EPSS Score

Percentile: 9%

Vendor	Product	Version
cisco	meraki_mx65_firmware	17.6.0 ≤ 𝑥 < 18.211.2
cisco	meraki_mx64_firmware	17.6.0 ≤ 𝑥 < 18.211.2
cisco	meraki_z4c_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_z4_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_z3c_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_z3_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_vmx_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx600_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx450_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx400_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx250_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx105_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx100_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx95_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx85_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx84_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx75_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx68w_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx68cw_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx68_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx67w_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx67c_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx67_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx65w_firmware	16.2 ≤ 𝑥 < 18.211.2
cisco	meraki_mx64w_firmware	16.2 ≤ 𝑥 < 18.211.2

𝑥

= Vulnerable software versions

Common Weakness Enumeration

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-meraki-mx-vpn-dos-by-QWUkqV7X