CVE-2025-15387VulnerabilityPublished 31 Dec 2025

CVE-2025-15387: QNO Technology VPN Firewall · Insufficient Entropy

Affects QNO Technology VPN FirewallSource CVE Database V5

Not known to be exploited · CVSS 8.7 High.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 4.0 base score

8.7High

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 30% 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:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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

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: Passive: Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker’s payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the vulnerable system. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the vulnerable system.
Vulnerable system availability: High: There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
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.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 31 Dec 2025
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 2026-10-26.

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
QNO Technology VPN Firewall	Affected =0	Fixed in–

AI-suggested

Immediate mitigation steps include: 1) Monitoring network traffic and VPN firewall logs for unusual brute-force attempts or anomalous session activities indicative of token guessing attacks. 2) Implementing network segmentation to isolate VPN firewalls from less trusted networks and limit attacker lateral movement if compromise occurs. 3) Applying strict rate limiting and account lockout policies on VPN login attempts to hinder brute-force exploitation. 4) Deploying multi-factor authentication (MFA) for VPN access to add an additional security layer beyond session tokens. 5) Restricting administrative access to VPN firewalls to trusted IP addresses and using out-of-band management where possible. 6) Preparing for patch deployment by engaging with QNO Technology for updates or workarounds, and testing patches in controlled environments before production rollout. 7) Educating security teams about this vulnerability to ensure rapid detection and response. 8) Considering temporary alternative VPN solutions if patching is delayed, to maintain secure remote access.

Description

CVE-2025-15387 is a high-severity vulnerability in QNO Technology's VPN Firewall caused by insufficient entropy in session token generation. This flaw allows unauthenticated remote attackers to perform brute-force attacks to obtain active user sessions and subsequently log into the system without credentials. The vulnerability does not require prior authentication or special privileges, and no user interaction is needed. Exploitation could lead to full compromise of VPN firewall devices, exposing sensitive network traffic and internal resources. Although no known exploits are currently in the wild, the ease of exploitation and critical impact on confidentiality, integrity, and availability make this a significant threat. European organizations using QNO VPN Firewalls are at risk, especially those in sectors with high reliance on secure remote access. Mitigation requires immediate implementation of patches once available, enhanced monitoring for brute-force attempts, and network segmentation to limit exposure. Countries with notable QNO market presence and strategic infrastructure, such as Germany, France, and the UK, are likely to be most affected. Defenders should prioritize this vulnerability due to its potential to enable unauthorized access and lateral movement within networks.

Impact

For European organizations, the impact of CVE-2025-15387 is substantial. VPN firewalls are pivotal in securing remote access and protecting internal networks from external threats. Exploitation of this vulnerability could lead to unauthorized access to sensitive corporate networks, exposing confidential data and intellectual property. Attackers could intercept or manipulate VPN traffic, leading to data breaches or espionage. The integrity of network security policies could be compromised, allowing attackers to deploy malware or conduct lateral movement within the network. Availability could also be affected if attackers disrupt VPN services or lock out legitimate users. Sectors such as finance, government, healthcare, and critical infrastructure in Europe, which heavily rely on secure VPN connections, would face elevated risks. The vulnerability's ease of exploitation and lack of authentication requirements increase the likelihood of attacks, potentially resulting in significant operational disruption and financial losses.

Summary

CVE-2025-15387 identifies a critical security vulnerability in the VPN Firewall product developed by QNO Technology, classified under CWE-331 (Insufficient Entropy). The root cause is the generation of session tokens or cryptographic values with insufficient randomness, which significantly weakens the security of user session management. This weakness enables unauthenticated remote attackers to conduct brute-force attacks against session tokens, allowing them to hijack any logged-in user session without needing valid credentials or prior authentication. The vulnerability affects all versions of the product (noted as version 0, likely indicating all current releases). The CVSS 4.0 base score of 8.7 reflects the high impact and ease of exploitation: the attack vector is network-based (AV:N), requires no privileges (PR:N), no authentication (AT:N), and no user interaction (UI:P). The vulnerability severely compromises confidentiality, integrity, and availability (VC:H, VI:H, VA:H) of the affected systems. Once exploited, attackers can gain unauthorized access to the VPN firewall's administrative interface or user sessions, potentially allowing them to intercept or manipulate VPN traffic, disrupt network operations, or pivot to internal networks. No patches are currently available, and no known exploits have been observed in the wild, but the vulnerability's characteristics suggest it could be weaponized rapidly. The vulnerability's presence in a VPN firewall—a critical network security device—amplifies its risk, as it can undermine the security perimeter of organizations relying on QNO Technology's products for secure remote access.

CWE-331Insufficient Entropy (opens in a new tab)
Base weaknessOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product uses an algorithm or scheme that produces insufficient entropy, leaving patterns or clusters of values that are more likely to occur than others.
Implementation
Determine the necessary entropy to adequately provide for randomness and predictability. This can be achieved by increasing the number of bits of objects such as keys and seeds.
OWASP Cheat Sheets
Session Management (opens in a new tab)
Transport Layer Protection (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
Cryptographic Storage (opens in a new tab)
OWASP ASVS 4.0.3
V3.2.2 (opens in a new tab)
V3.2.4 (opens in a new tab)
V2.3.1 (opens in a new tab)
Attack patterns
Session Credential Falsification through Prediction (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Jan 2026, 13:05 UTC

WeaknessesCWE-331

Technical details

References

Community reviews

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