CVE-2025-6669VulnerabilityPublished 25 Jun 2025Updated 1 Jul 2025

CVE-2025-6669: gooaclok819 sublinkX · Use of Hard-coded Cryptographic Key

Affects gooaclok819 sublinkXSource CVE Database V5

Not known to be exploited · CVSS 6.3 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

6.3Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:H/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: High
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: High: The successful attack depends on the evasion or circumvention of security-enhancing techniques in place that would otherwise hinder the attack. These include: Evasion of exploit mitigation techniques, for example, circumvention of address space randomization (ASLR) or data execution prevention (DEP) must be performed for the attack to be successful; Obtaining target-specific secrets. The attacker must gather some target-specific secret before the attack can be successful. A secret is any piece of information that cannot be obtained through any amount of reconnaissance. To obtain the secret the attacker must perform additional attacks or break otherwise secure measures (e.g. knowledge of a secret key may be needed to break a crypto channel). This operation must be performed for each attacked target.
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 25 Jun 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

Affected software

Product	Affected	Fixed in
GitHubgooaclok819/sublinkX`pkg:github/gooaclok819/sublinkX`Other threats	Affected =1.0 =1.1 =1.2 =1.3 =1.4 =1.5 =1.6 =1.7 =1.8	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Immediate upgrade to sublinkX version 1.9 or later, which contains the patch removing the hard-coded cryptographic key and implementing secure key management practices. 2. Conduct a thorough audit of all systems using sublinkX to identify affected versions and ensure no legacy instances remain unpatched. 3. Review and rotate any cryptographic keys or tokens that may have been generated or validated using the vulnerable versions to prevent misuse. 4. Implement additional monitoring on authentication and authorization logs to detect anomalous JWT usage or token forgery attempts. 5. Employ defense-in-depth by integrating multi-factor authentication (MFA) where possible to reduce reliance solely on JWT tokens. 6. For development teams, enforce secure coding standards that prohibit hard-coded cryptographic keys and promote the use of environment-based or hardware security module (HSM) key storage. 7. Engage in threat hunting exercises focused on detecting exploitation attempts related to this vulnerability, especially given the public disclosure of exploit code. 8. Coordinate with software vendors and security teams to stay informed about any emerging exploit techniques or additional patches.

Description

A vulnerability was found in gooaclok819 sublinkX up to 1.8. It has been declared as problematic. This vulnerability affects unknown code of the file middlewares/jwt.go. The manipulation with the input sublink leads to use of hard-coded cryptographic key . The attack can be initiated remotely. The complexity of an attack is rather high. The exploitation appears to be difficult. The exploit has been disclosed to the public and may be used. Upgrading to version 1.9 is able to address this issue. The patch is identified as 778d26aef723daa58df98c8060c43f5bf5d1b10b. It is recommended to upgrade the affected component.

Impact

For European organizations, the use of a hard-coded cryptographic key in sublinkX could lead to token forgery or manipulation, potentially allowing unauthorized access to protected resources or services that rely on JWT for authentication or authorization. This could compromise the integrity of user sessions or API calls, leading to unauthorized data access or privilege escalation within applications using sublinkX middleware. While the direct impact on confidentiality and availability is limited, the integrity compromise could facilitate further attacks or data breaches. Organizations in sectors with high reliance on secure token-based authentication, such as finance, healthcare, and critical infrastructure, may face increased risk. Additionally, the public availability of exploit details raises the likelihood of targeted attacks, especially against entities that have not applied the patch. The medium severity rating suggests that while the vulnerability is not trivial, it should not be underestimated, particularly in environments where sublinkX is a core component of security infrastructure.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Jun 2025, 22:57 UTC

Technical details

References

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