CVE-2025-54870VulnerabilityPublished 5 Aug 2025

CVE-2025-54870: leakingmemory vtun-ng · Failing Open

Affects leakingmemory vtun-ngSource CVE Database V5

Not known to be exploited · CVSS 8.7 High · fixed in 3.0.18 : patch leakingmemory vtun-ng soon.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

8.7High

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.0.18

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: None
Vulnerable system availability: None
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: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
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: 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.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 Aug 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 2026-10-25.

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

AI-suggested

1. Immediate upgrade to VTun-ng version 3.0.18 or later, where the vulnerability is fixed, is the most effective mitigation. 2. Until upgrading, avoid using the blowfish-256 encryption algorithm, as it is linked to the failure condition. 3. Implement network monitoring to detect unencrypted VTun-ng traffic, which may indicate exploitation or failure conditions. 4. Use additional layers of encryption such as IPsec or TLS tunnels over VTun-ng to protect data in transit as a defense-in-depth measure. 5. Conduct thorough configuration reviews and testing after upgrades to ensure encryption modules initialize correctly and no fallback to plaintext occurs. 6. Restrict VTun-ng usage to trusted network segments and limit exposure to untrusted networks to reduce the risk of interception. 7. Educate network administrators about the vulnerability and the importance of timely patching and configuration management. 8. Consider alternative VPN or tunneling solutions with robust security track records if VTun-ng cannot be updated promptly.

Description

VTun-ng is a Virtual Tunnel over TCP/IP network. In versions 3.0.17 and below, failure to initialize encryption modules might cause reversion to plaintext due to insufficient error handling. The bug was first introduced in VTun-ng version 3.0.12. This is fixed in version 3.0.18. To workaround this issue, avoid blowfish-256.

Impact

For European organizations, this vulnerability poses a significant risk to the confidentiality of data transmitted over VTun-ng tunnels. Organizations using VTun-ng for secure communications, remote access, or site-to-site VPNs could inadvertently expose sensitive information such as intellectual property, personal data protected under GDPR, or confidential business communications. The failure to securely initialize encryption could allow attackers on the network path to capture unencrypted traffic, leading to data breaches and compliance violations. This is particularly critical for sectors handling sensitive or regulated data, including finance, healthcare, government, and critical infrastructure. The lack of required authentication or user interaction for exploitation increases the risk, as attackers can passively intercept traffic without alerting users. The vulnerability also undermines trust in the security of VTun-ng tunnels, potentially forcing organizations to seek alternative secure communication solutions if patches cannot be applied promptly.

CWE-636Not Failing Securely ('Failing Open') (opens in a new tab)
Class weaknessOWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions.
Architecture and Design
Subdivide and allocate resources and components so that a failure in one part does not affect the entire product.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (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

Description

AI analysisMachine-generated, updated 5 Aug 2025, 01:02 UTC

WeaknessesCWE-636

Technical details

References

Community reviews

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