CVE-2026-40514
Cryptographic Weakness in SmarterMail Enables Unauthorized Data Forgery
Publication date: 2026-04-27
Last updated on: 2026-04-27
Assigner: VulnCheck
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| smartertools | smartermail | to 9610 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-338 | The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong. |
Attack-Flow Graph
AI Powered Q&A
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The vulnerability allows an unauthenticated attacker to forge sharing tokens and access arbitrary emails, attachments, or file storage contents without prior access. This results in a high impact on confidentiality of sensitive data.
Such unauthorized access to sensitive information can lead to non-compliance with common data protection standards and regulations like GDPR and HIPAA, which mandate strict controls over the confidentiality and protection of personal and health-related data.
Can you explain this vulnerability to me?
CVE-2026-40514 affects SmarterTools SmarterMail versions prior to Build 9610 and involves a cryptographic weakness caused by the use of a weak pseudo-random number generator (PRNG). The file and email sharing endpoints use DES-CBC encryption with keys and initialization vectors derived from System.Random, which is seeded with insufficient entropy. This weak seeding limits the seed space to about 19,000 possible values, making it vulnerable to attack.
An unauthenticated attacker can exploit the attachment download endpoint as an oracle to determine the seed value in use. Once the seed is known, the attacker can derive the encryption keys and initialization vectors, allowing them to forge sharing tokens for arbitrary emails, attachments, or file storage contents without prior access to the targeted data.
How can this vulnerability impact me? :
This vulnerability can have a significant impact on confidentiality. An attacker can forge sharing tokens to access arbitrary emails, attachments, or file storage contents without any prior access or authentication.
Because the attack requires no privileges or user interaction and can be performed remotely over the network, it poses a high risk of unauthorized data exposure.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability affects SmarterTools SmarterMail versions prior to Build 9610 that use DES-CBC encryption with keys and IVs derived from System.Random seeded with insufficient entropy.
To detect this vulnerability on your system, you should verify the version of SmarterMail installed and check if it is prior to Build 9610.
Additionally, monitoring network traffic for suspicious activity targeting the attachment download endpoint could indicate exploitation attempts.
Specific commands to check the SmarterMail version might include:
- On Windows servers, use PowerShell: Get-ItemProperty -Path 'HKLM:\Software\SmarterTools\SmarterMail' | Select-Object Version
- Check the application version via the SmarterMail web interface or its about page.
- Use network monitoring tools (e.g., Wireshark, tcpdump) to capture traffic to the attachment download endpoint and analyze for unusual requests.
What immediate steps should I take to mitigate this vulnerability?
The primary mitigation step is to upgrade SmarterTools SmarterMail to Build 9610 or later, where this cryptographic weakness has been addressed.
Until the upgrade can be applied, consider restricting network access to the file and email sharing endpoints to trusted users only, reducing exposure to unauthenticated attackers.
Monitor logs and network traffic for suspicious activity targeting the attachment download endpoint to detect potential exploitation attempts.