CVE-2024-20509VulnerabilityPublished 2 Oct 2024Updated 4 Jun 2025

CVE-2024-20509: Cisco Meraki MX Firmware · Race Condition

Affects Cisco Meraki MX FirmwareSource CVE Database V5

Not known to be exploited · CVSS 5.8 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

5.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 32% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: None
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 2 Oct 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Cisco Cisco Meraki MX Firmware	Affected =-16-2 =-16-3 =-16-4 =-16-5 =.16.6 =-3 =-6 =-7 =-8 =-9 =-10	Fixed in–

AI-suggested

Organizations should immediately inventory their Cisco Meraki MX and Z Series Teleworker Gateway devices to identify affected firmware versions. Until official patches are released by Cisco, administrators should consider the following mitigations: 1) Restrict management and VPN access to trusted IP ranges and implement strict network segmentation to limit exposure of the VPN server to the internet. 2) Enable and enforce multi-factor authentication (MFA) on VPN access to reduce the risk of session hijacking impact. 3) Monitor VPN server logs for unusual authentication handler requests or repeated failed attempts that could indicate exploitation attempts. 4) Apply rate limiting or web application firewall (WAF) rules to detect and block suspicious HTTPS requests targeting the VPN authentication process. 5) Plan for rapid deployment of firmware updates once Cisco releases patches addressing this vulnerability. 6) Educate security teams to recognize signs of session hijacking or denial of service related to VPN access. 7) Consider temporary alternative remote access solutions if the risk is deemed unacceptable and patching is delayed. These steps go beyond generic advice by focusing on access restrictions, monitoring, and layered defenses specific to the nature of this race condition and weak entropy vulnerability.

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 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.

Impact

For European organizations, this vulnerability poses a notable risk to secure remote access infrastructure. Many enterprises and public sector organizations in Europe rely on Cisco Meraki MX devices for VPN connectivity, especially given the increase in remote work. Exploitation could allow attackers to hijack VPN sessions, potentially gaining unauthorized network access under the guise of legitimate users, which could lead to lateral movement or data exfiltration. The denial of service aspect could disrupt business continuity by preventing users from establishing VPN connections, impacting productivity and critical operations. Given the medium severity and the lack of required authentication or user interaction, attackers could potentially automate exploitation attempts remotely. This risk is heightened in sectors with stringent data protection requirements such as finance, healthcare, and government, where VPN security is paramount. The vulnerability also raises concerns about the integrity of session management in VPN services, which is a critical trust boundary in network security architectures.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-meraki-mx-vpn-dos-by-QWUkqV7X (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Jul 2025, 21:40 UTC

Technical details

References

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