VulnerabilityPublished 9 Jun 2025

CVE-2025-5876: Lucky LM-520-SC · Missing Authentication

Affects Lucky LM-520-SCSource CVE Database V5

Public exploit available · CVSS 6.9 Medium.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

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 or the CVSS exploit maturity 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
Lucky LM-520-SC	Affected =20250321	Fixed in–

AI-suggested

Given the absence of vendor patches, European organizations should implement immediate compensating controls. First, restrict network access to the affected devices by segmenting them into isolated network zones with strict firewall rules allowing only trusted management hosts. Employ network-level authentication and VPNs to limit exposure. Continuous monitoring of network traffic to and from these devices should be established to detect anomalous access attempts. If possible, disable or restrict the vulnerable functionality until a patch or vendor guidance is available. Employ intrusion detection or prevention systems (IDS/IPS) with signatures or heuristics tuned to detect exploitation attempts targeting this vulnerability. Regularly audit device configurations and logs for unauthorized access indicators. Organizations should also engage with the vendor for updates and consider alternative devices if remediation is not forthcoming. Finally, maintain up-to-date asset inventories to identify all affected devices and prioritize mitigation efforts accordingly.

Description

A vulnerability classified as problematic was found in Lucky LM-520-SC, LM-520-FSC and LM-520-FSC-SAM up to 20250321. Affected by this vulnerability is an unknown functionality. The manipulation leads to missing authentication. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Impact

For European organizations using Lucky LM-520 series devices, this vulnerability poses a tangible risk of unauthorized remote access. Depending on the deployment context—such as industrial control systems, telecommunications infrastructure, or other critical operational environments—attackers could exploit this flaw to gather sensitive information, disrupt operations, or pivot to other internal systems. The lack of authentication means that any attacker with network access to these devices could attempt exploitation, potentially leading to breaches of confidentiality or unauthorized configuration changes. The public disclosure of the exploit increases the urgency for mitigation, as threat actors may develop or adapt tools to exploit this vulnerability. Organizations in sectors with high reliance on these devices, such as manufacturing, utilities, or communications, could face operational disruptions or data leaks. Additionally, the vendor's non-responsiveness and absence of patches exacerbate the risk, forcing organizations to rely on compensating controls. The medium severity rating reflects limited impact on integrity and availability but does not diminish the risk of unauthorized access and information exposure. European entities must consider the potential for targeted attacks, especially in critical infrastructure or high-value environments where these devices are deployed.

References

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