Overview
CVE-2025-54320 describes a vulnerability in Ascertia SigningHub, specifically affecting versions up to 8.6.8. This vulnerability arises from the absence of proper rate limiting on the “invite user” function. An authenticated attacker can leverage this weakness to perform an email bombing attack by automating a large number of invite requests. This can overwhelm targeted users with unwanted emails and potentially disrupt normal operations.
Technical Details
The core issue lies in the lack of rate limiting for the invite user functionality within SigningHub. This allows an attacker, after successfully authenticating to the system (with appropriate privileges to invite users), to programmatically send numerous invite requests in a short period. These requests trigger the system to send out email invitations to the specified email addresses. Without rate limiting in place, the attacker can flood the target’s inbox, effectively creating an email bombing scenario.
The vulnerability is exploitable by crafting automated requests to the invite user endpoint. An attacker could use scripts or tools to repeatedly send these requests, bypassing any manual limitations that might be present in the user interface. The severity of this attack depends on factors like the attacker’s available resources and the system’s overall capacity to handle email requests.
CVSS Analysis
Currently, both the severity and CVSS score for CVE-2025-54320 are listed as N/A. This may be because the CVSS score is pending assignment or because the severity is considered informational. However, the potential for disruption and resource exhaustion suggests that it could be classified with at least a medium severity once a CVSS score is assigned. A more accurate score calculation will be necessary based on factors such as scope change, confidentiality impact, integrity impact and availability impact.
Possible Impact
The successful exploitation of CVE-2025-54320 can lead to several negative consequences:
- Email Inbox Overload: Targeted users’ inboxes become flooded with unwanted invite emails, potentially burying legitimate communications.
- Denial of Service (DoS): The influx of emails can overwhelm mail servers, leading to delays or failures in email delivery for all users.
- Resource Exhaustion: The constant processing and sending of emails can strain SigningHub’s server resources, impacting performance and potentially causing instability.
- Brand Reputation Damage: If the attack is widespread and public, it can damage Ascertia’s reputation and erode trust in SigningHub.
Mitigation or Patch Steps
The primary mitigation strategy involves implementing rate limiting on the invite user function within SigningHub. Ascertia should release a patch that includes the following measures:
- Rate Limiting Implementation: Enforce a maximum number of invite requests that can be sent from a single account or IP address within a specific timeframe.
- CAPTCHA Integration: Implement CAPTCHA or similar mechanisms to prevent automated bots from sending invite requests.
- Account Lockout Policies: Implement account lockout policies to prevent abuse.
- Input Validation: Implement robust input validation to prevent malformed or malicious invite requests.
Users of Ascertia SigningHub are advised to update to the latest patched version as soon as it becomes available. In the interim, administrators should monitor the usage of the invite user function and consider temporarily disabling it if suspicious activity is detected.
