CVE-2026-40514: CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in SmarterTools Inc. SmarterMail
SmarterTools SmarterMail builds prior to 9610 contain a cryptographic weakness in the file and email sharing endpoints that use DES-CBC encryption with keys and initialization vectors derived from System.Random seeded with insufficient entropy, reducing the seed space to approximately 19,000 possible values. An unauthenticated attacker can use the attachment download endpoint as an oracle to determine the seed in use and derive encryption keys and initialization vectors to forge sharing tokens for arbitrary emails, attachments, or file storage contents without prior access to the targeted content.
AI Analysis
Technical Summary
CVE-2026-40514 describes a cryptographic weakness in SmarterTools SmarterMail builds before version 9610. The vulnerability arises because the file and email sharing endpoints use DES-CBC encryption with keys and IVs derived from System.Random seeded with low entropy, reducing the seed space to approximately 19,000 possible values. An unauthenticated attacker can leverage the attachment download endpoint as an oracle to determine the seed, then derive the encryption keys and IVs. This enables the attacker to forge sharing tokens for arbitrary content without needing prior access, compromising confidentiality and integrity of shared files and emails.
Potential Impact
The vulnerability allows unauthenticated attackers to forge sharing tokens for arbitrary emails, attachments, or file storage contents. This compromises the confidentiality and integrity of shared content by enabling unauthorized access and manipulation without prior access. The cryptographic weakness in key generation significantly reduces the effort needed to break the encryption protecting shared resources.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch information is provided at this time. Until a patch is available, restrict access to the affected endpoints and monitor for suspicious activity related to sharing token usage.
CVE-2026-40514: CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in SmarterTools Inc. SmarterMail
Description
SmarterTools SmarterMail builds prior to 9610 contain a cryptographic weakness in the file and email sharing endpoints that use DES-CBC encryption with keys and initialization vectors derived from System.Random seeded with insufficient entropy, reducing the seed space to approximately 19,000 possible values. An unauthenticated attacker can use the attachment download endpoint as an oracle to determine the seed in use and derive encryption keys and initialization vectors to forge sharing tokens for arbitrary emails, attachments, or file storage contents without prior access to the targeted content.
CVSS v4.0
Score 8.2high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-40514 describes a cryptographic weakness in SmarterTools SmarterMail builds before version 9610. The vulnerability arises because the file and email sharing endpoints use DES-CBC encryption with keys and IVs derived from System.Random seeded with low entropy, reducing the seed space to approximately 19,000 possible values. An unauthenticated attacker can leverage the attachment download endpoint as an oracle to determine the seed, then derive the encryption keys and IVs. This enables the attacker to forge sharing tokens for arbitrary content without needing prior access, compromising confidentiality and integrity of shared files and emails.
Potential Impact
The vulnerability allows unauthenticated attackers to forge sharing tokens for arbitrary emails, attachments, or file storage contents. This compromises the confidentiality and integrity of shared content by enabling unauthorized access and manipulation without prior access. The cryptographic weakness in key generation significantly reduces the effort needed to break the encryption protecting shared resources.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch information is provided at this time. Until a patch is available, restrict access to the affected endpoints and monitor for suspicious activity related to sharing token usage.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-04-13T20:29:02.809Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69ef79fcba26a39fba368ba3
Added to database: 04/27/2026, 15:00:12 UTC
Last enriched: 07/15/2026, 10:28:05 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 108
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