The landscape of cybersecurity is constantly evolving, with new vulnerabilities being discovered and disclosed regularly. The Common Vulnerabilities and Exposures (CVE) system plays a crucial role in cataloging these security weaknesses, providing a standardized method for identification and communication.
This report focuses on a recently published CVE, specifically CVE-2025-4528, which details a vulnerability found in Dígitro NGC Explorer up to version 3.44.15. 1 This analysis will delve into the nature of the vulnerability, its potential impact, and available information regarding its discovery and mitigation.
Understanding Insufficient Session Expiration (CWE-613)
CVE-2025-4528 is classified as an "Insufficient Session Expiration" vulnerability, identified under the Common Weakness Enumeration (CWE) code CWE-613. 1 This category of vulnerability arises when a web application allows an attacker to reuse old session credentials or session identifiers for authorization.
In essence, if a user's session is not properly terminated or expires after an appropriate period of inactivity, there's a risk that malicious actors could potentially hijack that session and gain unauthorized access to the user's account or the application's functionalities. 2
To understand this further, it's important to distinguish between two types of session timeouts: inactivity and absolute. An inactivity timeout refers to the amount of idle time permitted before a session is automatically invalidated. Conversely, an absolute timeout defines the total duration a session can remain valid, regardless of user activity, without requiring re-authentication. The absence of proper session expiration mechanisms, or the use of excessively long timeout periods, significantly increases a website's susceptibility to attacks aimed at stealing or reusing session identifiers.2
Since web applications often rely on cookies to store session IDs that uniquely identify a user across multiple requests, the confidentiality of these session IDs is paramount. If a session ID is compromised, it can be exploited to view another user's account or perform fraudulent actions. 2 A discussion on Reddit highlights that even with secure and HTTP-only cookies, if the session ID itself isn't invalidated on the server-side upon logout, a stolen cookie could remain valid until its natural expiration. 3 This underscores the critical need for robust server-side session management.
CVE-2025-4528: Specific Vulnerability Details
The specific instance of insufficient session expiration identified as CVE-2025-4528 affects Dígitro NGC Explorer up to version 3.44.15.1 According to the information available, the vulnerability lies within "some unknown processing" of the software. The manipulation of this unknown processing leads to the expiration of user sessions. Notably, the attack exploiting this vulnerability can be initiated remotely. 1
The details of this vulnerability were initially reported by VulDB, a vulnerability database. It is important to acknowledge the role of such databases in the early identification and disclosure of potential security threats. While the information has been included in the National Vulnerability Database (NVD), the primary source remains VulDB in this instance. 1
A significant point of concern is the reported lack of response from the vendor, Dígitro, despite early attempts to contact them regarding this disclosure. This absence of vendor communication leaves users of the affected software without official guidance on remediation or mitigation, emphasizing the need for proactive security measures based on the available information. 1
Impact Analysis
The potential impact of an attacker being able to cause session expirations in Dígitro NGC Explorer warrants careful consideration. While the vulnerability description explicitly mentions "session expiration," the implications extend beyond a mere inconvenience to users. Prematurely terminated sessions can disrupt user workflows, potentially leading to data loss if critical operations are interrupted.
Furthermore, depending on the nature of the "unknown processing" involved, an attacker might be able to exploit this vulnerability to not only force session terminations but also to potentially manipulate system states or gain unauthorized access during the window of opportunity before the forced expiration. The exact nature of this manipulation remains unclear given the limited details provided.
To better understand the severity of this vulnerability, it is crucial to examine the Common Vulnerability Scoring System (CVSS) scores assigned by VulDB.1 These scores provide a standardized numerical representation of the vulnerability's severity. The following table summarizes the CVSS scores for CVE-2025-4528:
The CVSS v3.1 vector string (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N) provides valuable insights into the characteristics of the attack. "AV:N" indicates that the attack can be carried out over a network, highlighting its potential reach. "AC:L" signifies a low attack complexity, meaning the conditions required to exploit the vulnerability are easily met. "PR:L" suggests that an attacker needs low privileges to execute the attack, implying that even regular users with limited access could potentially trigger it. "UI:N" denotes that no user interaction is required for the attack to succeed. "S:U" indicates that the vulnerability's scope is limited to the affected software component. Finally, "C:N/I:L/A:N" reveals that there is no impact on confidentiality, a low impact on integrity (potentially allowing for some unauthorized modifications), and no impact on availability (in terms of system downtime, though session disruption could be considered a temporary denial of service).
The CVSS v2.0 vector string (AV:N/AC:L/Au:S/C:N/I:P/A:N) shows some similarities but also a key difference. "AV:N" and "AC:L" align with the v3.1 score. However, "Au:S" indicates that authentication is required to exploit the vulnerability, suggesting that the attacker would need to have some form of valid credentials, even if low-privileged. This differs slightly from the v3.1 score's "PR:L" (low privileges), which could encompass scenarios where an attacker has already gained some level of access. The impact scores in v2.0 ("C:N/I:P/A:N") also point to no impact on confidentiality, but a potential for partial impact on integrity.
Technical Overview
As previously mentioned, CVE-2025-4528 is categorized as CWE-613: Insufficient Session Expiration. 1 This weakness fundamentally relates to how a web application manages and invalidates user sessions. When sessions are not properly terminated or expire too late, it creates a window of opportunity for attackers to potentially exploit compromised session tokens.
While the vulnerability description states that it "leads to session expiration," the CWE title suggests that the core issue might be that sessions are not being invalidated promptly or under appropriate conditions. This could mean that even after a user logs out, their session might remain active on the server for an extended period, making it vulnerable if the session identifier is obtained by a malicious actor.
Affected Product
The product affected by this vulnerability is clearly identified as Dígitro NGC Explorer up to version 3.44.15.1 Based on available information, Dígitro NGC Explorer is a platform designed for complex solutions requiring data routing, significant telephony resources, and convergent connectivity, built upon CT technology. 4
It offers features such as PABX, DAC, URA, MUX, Softswitch, Gateway, and Router functionalities, indicating its potential role as a critical component within an organization's communication and data infrastructure. Mentions of "DÍGITRO SmartCell" and "NGC EVOLUTION" in other contexts suggest a family of related products from the same vendor. 5 As noted earlier, a significant concern surrounding this vulnerability is the lack of any response from Dígitro after being notified of the issue. 1
Exploitation Scenarios
Given the nature of insufficient session expiration, several potential exploitation scenarios could arise for CVE-2025-4528. If an attacker manages to gain access to a valid session token of a user (through methods such as network sniffing, exploiting a cross-site scripting vulnerability if one exists elsewhere in the application, or through social engineering tactics), they could potentially use this token to impersonate the legitimate user. 2 This could occur even after the legitimate user has logged out, as the session might still be active on the server until its natural expiration.
Furthermore, while the primary outcome described is "session expiration," the CVSS score indicating a low impact on integrity suggests a more nuanced exploitation possibility. An attacker might be able to manipulate the conditions that trigger the session expiration in a way that allows them to modify data or system states within the application before the session is forcibly terminated. However, the specifics of this remain unclear due to the lack of detailed information about the "unknown processing" affected by the vulnerability.
Another potential scenario involves an attacker repeatedly exploiting the vulnerability to force session expirations for legitimate users, potentially leading to a form of denial-of-service by disrupting their access and workflows.
Mitigation Strategies
Due to the absence of a vendor response and a specific patch for CVE-2025-4528 at this time, users of Dígitro NGC Explorer up to version 3.44.15 should consider implementing general best practices for mitigating insufficient session expiration vulnerabilities. 2
- Implement Strong Session Management: Ensure that session IDs are generated using cryptographically strong random numbers, are protected during transmission (ideally through HTTPS encryption), and are stored securely on the server-side.
- Enforce Appropriate Session Timeouts: Define and enforce both inactivity and absolute session timeouts that are appropriate for the sensitivity of the application and typical user activity patterns. Consider shortening these timeouts where feasible to minimize the window of opportunity for attackers.
- Invalidate Sessions on Logout: When a user logs out, the application must explicitly invalidate the corresponding session on the server-side and destroy the associated session token. Simply deleting the client-side cookie is not sufficient.
- Regular Security Audits: Conduct regular security audits and penetration testing specifically focusing on session management mechanisms to identify and address any potential weaknesses.
- Web Application Firewall (WAF): Deploy and properly configure a Web Application Firewall that can help detect and block malicious attempts to manipulate sessions or exploit known vulnerabilities.
- Monitor for Suspicious Activity: Implement robust logging and monitoring systems to detect any unusual session activity, unauthorized access attempts, or patterns of forced session expirations.
- Consider Alternative Solutions: If Dígitro NGC Explorer is a critical component and a timely patch is not forthcoming, organizations should explore alternative solutions or configurations that might mitigate the risk. In more severe cases, considering a migration to a more actively supported and responsive product might be necessary.
- Stay Informed: Continuously monitor for any updates, advisories, or workarounds related to this vulnerability from the vendor or the broader security community.
Final Thoughts
CVE-2025-4528 represents a medium severity vulnerability affecting Dígitro NGC Explorer up to version 3.44.15, stemming from insufficient session expiration. This flaw could allow attackers to cause session expirations and potentially achieve a low impact on data integrity. The lack of response from the vendor, Dígitro, to the vulnerability disclosure is a significant concern, leaving users without specific remediation guidance.
Given this situation, it is imperative for organizations utilizing the affected software to implement proactive mitigation strategies, focusing on robust session management practices, appropriate timeouts, and diligent monitoring for any suspicious activity. The ongoing nature of cybersecurity threats necessitates continuous vigilance and a commitment to addressing vulnerabilities promptly to protect systems and data.
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